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* mempolicy: use MPOL_PREFERRED for system-wide default policyLee Schermerhorn2008-04-28
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Currently, when one specifies MPOL_DEFAULT via a NUMA memory policy API [set_mempolicy(), mbind() and internal versions], the kernel simply installs a NULL struct mempolicy pointer in the appropriate context: task policy, vma policy, or shared policy. This causes any use of that policy to "fall back" to the next most specific policy scope. The only use of MPOL_DEFAULT to mean "local allocation" is in the system default policy. This requires extra checks/cases for MPOL_DEFAULT in many mempolicy.c functions. There is another, "preferred" way to specify local allocation via the APIs. That is using the MPOL_PREFERRED policy mode with an empty nodemask. Internally, the empty nodemask gets converted to a preferred_node id of '-1'. All internal usage of MPOL_PREFERRED will convert the '-1' to the id of the node local to the cpu where the allocation occurs. System default policy, except during boot, is hard-coded to "local allocation". By using the MPOL_PREFERRED mode with a negative value of preferred node for system default policy, MPOL_DEFAULT will never occur in the 'policy' member of a struct mempolicy. Thus, we can remove all checks for MPOL_DEFAULT when converting policy to a node id/zonelist in the allocation paths. In slab_node() return local node id when policy pointer is NULL. No need to set a pol value to take the switch default. Replace switch default with BUG()--i.e., shouldn't happen. With this patch MPOL_DEFAULT is only used in the APIs, including internal calls to do_set_mempolicy() and in the display of policy in /proc/<pid>/numa_maps. It always means "fall back" to the the next most specific policy scope. This simplifies the description of memory policies quite a bit, with no visible change in behavior. get_mempolicy() continues to return MPOL_DEFAULT and an empty nodemask when the requested policy [task or vma/shared] is NULL. These are the values one would supply via set_mempolicy() or mbind() to achieve that condition--default behavior. This patch updates Documentation to reflect this change. Signed-off-by: Lee Schermerhorn <lee.schermerhorn@hp.com> Cc: Christoph Lameter <clameter@sgi.com> Cc: David Rientjes <rientjes@google.com> Cc: Mel Gorman <mel@csn.ul.ie> Cc: Andi Kleen <ak@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mempolicy: rework mempolicy Reference Counting [yet again]Lee Schermerhorn2008-04-28
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | After further discussion with Christoph Lameter, it has become clear that my earlier attempts to clean up the mempolicy reference counting were a bit of overkill in some areas, resulting in superflous ref/unref in what are usually fast paths. In other areas, further inspection reveals that I botched the unref for interleave policies. A separate patch, suitable for upstream/stable trees, fixes up the known errors in the previous attempt to fix reference counting. This patch reworks the memory policy referencing counting and, one hopes, simplifies the code. Maybe I'll get it right this time. See the update to the numa_memory_policy.txt document for a discussion of memory policy reference counting that motivates this patch. Summary: Lookup of mempolicy, based on (vma, address) need only add a reference for shared policy, and we need only unref the policy when finished for shared policies. So, this patch backs out all of the unneeded extra reference counting added by my previous attempt. It then unrefs only shared policies when we're finished with them, using the mpol_cond_put() [conditional put] helper function introduced by this patch. Note that shmem_swapin() calls read_swap_cache_async() with a dummy vma containing just the policy. read_swap_cache_async() can call alloc_page_vma() multiple times, so we can't let alloc_page_vma() unref the shared policy in this case. To avoid this, we make a copy of any non-null shared policy and remove the MPOL_F_SHARED flag from the copy. This copy occurs before reading a page [or multiple pages] from swap, so the overhead should not be an issue here. I introduced a new static inline function "mpol_cond_copy()" to copy the shared policy to an on-stack policy and remove the flags that would require a conditional free. The current implementation of mpol_cond_copy() assumes that the struct mempolicy contains no pointers to dynamically allocated structures that must be duplicated or reference counted during copy. Signed-off-by: Lee Schermerhorn <lee.schermerhorn@hp.com> Cc: Christoph Lameter <clameter@sgi.com> Cc: David Rientjes <rientjes@google.com> Cc: Mel Gorman <mel@csn.ul.ie> Cc: Andi Kleen <ak@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mempolicy: mark shared policies for unrefLee Schermerhorn2008-04-28
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | As part of yet another rework of mempolicy reference counting, we want to be able to identify shared policies efficiently, because they have an extra ref taken on lookup that needs to be removed when we're finished using the policy. Note: the extra ref is required because the policies are shared between tasks/processes and can be changed/freed by one task while another task is using them--e.g., for page allocation. Building on David Rientjes mempolicy "mode flags" enhancement, this patch indicates a "shared" policy by setting a new MPOL_F_SHARED flag in the flags member of the struct mempolicy added by David. MPOL_F_SHARED, and any future "internal mode flags" are reserved from bit zero up, as they will never be passed in the upper bits of the mode argument of a mempolicy API. I set the MPOL_F_SHARED flag when the policy is installed in the shared policy rb-tree. Don't need/want to clear the flag when removing from the tree as the mempolicy is freed [unref'd] internally to the sp_delete() function. However, a task could hold another reference on this mempolicy from a prior lookup. We need the MPOL_F_SHARED flag to stay put so that any tasks holding a ref will unref, eventually freeing, the mempolicy. A later patch in this series will introduce a function to conditionally unref [mpol_free] a policy. The MPOL_F_SHARED flag is one reason [currently the only reason] to unref/free a policy via the conditional free. Signed-off-by: Lee Schermerhorn <lee.schermerhorn@hp.com> Cc: Christoph Lameter <clameter@sgi.com> Cc: David Rientjes <rientjes@google.com> Cc: Mel Gorman <mel@csn.ul.ie> Cc: Andi Kleen <ak@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mempolicy: rename struct mempolicy 'policy' member to 'mode'Lee Schermerhorn2008-04-28
| | | | | | | | | | | | | | | | | | | | | | The terms 'policy' and 'mode' are both used in various places to describe the semantics of the value stored in the 'policy' member of struct mempolicy. Furthermore, the term 'policy' is used to refer to that member, to the entire struct mempolicy and to the more abstract concept of the tuple consisting of a "mode" and an optional node or set of nodes. Recently, we have added "mode flags" that are passed in the upper bits of the 'mode' [or sometimes, 'policy'] member of the numa APIs. I'd like to resolve this confusion, which perhaps only exists in my mind, by renaming the 'policy' member to 'mode' throughout, and fixing up the Documentation. Man pages will be updated separately. Signed-off-by: Lee Schermerhorn <lee.schermerhorn@hp.com> Cc: Christoph Lameter <clameter@sgi.com> Cc: David Rientjes <rientjes@google.com> Cc: Mel Gorman <mel@csn.ul.ie> Cc: Andi Kleen <ak@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mempolicy: fixup Fallback for Default Shmem PolicyLee Schermerhorn2008-04-28
| | | | | | | | | | | | | | | | | | | | | | | | get_vma_policy() is not handling fallback to task policy correctly when the get_policy() vm_op returns NULL. The NULL overwrites the 'pol' variable that was holding the fallback task mempolicy. So, it was falling back directly to system default policy. Fix get_vma_policy() to use only non-NULL policy returned from the vma get_policy op. shm_get_policy() was falling back to current task's mempolicy if the "backing file system" [tmpfs vs hugetlbfs] does not support the get_policy vm_op and the vma policy is null. This is incorrect for show_numa_maps() which is likely querying the numa_maps of some task other than current. Remove this fallback. Signed-off-by: Lee Schermerhorn <lee.schermerhorn@hp.com> Cc: Christoph Lameter <clameter@sgi.com> Cc: David Rientjes <rientjes@google.com> Cc: Mel Gorman <mel@csn.ul.ie> Cc: Andi Kleen <ak@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mempolicy: write lock mmap_sem while changing task mempolicyLee Schermerhorn2008-04-28
| | | | | | | | | | | | | | | | | | | | | | | | | | | | A read of /proc/<pid>/numa_maps holds the target task's mmap_sem for read while examining each vma's mempolicy. A vma's mempolicy can fall back to the task's policy. However, the task could be changing it's task policy and free the one that the show_numa_maps() is examining. To prevent this, grab the mmap_sem for write when updating task mempolicy. Pointed out to me by Christoph Lameter and extracted and reworked from Christoph's alternative mempol reference counting patch. This is analogous to the way that do_mbind() and do_get_mempolicy() prevent races between task's sharing an mm_struct [a.k.a. threads] setting and querying a mempolicy for a particular address. Note: this is necessary, but not sufficient, to allow us to stop taking an extra reference on "other task's mempolicy" in get_vma_policy. Subsequent patches will complete this update, allowing us to simplify the tests for whether we need to unref a mempolicy at various points in the code. Signed-off-by: Lee Schermerhorn <lee.schermerhorn@hp.com> Cc: Christoph Lameter <clameter@sgi.com> Cc: David Rientjes <rientjes@google.com> Cc: Mel Gorman <mel@csn.ul.ie> Cc: Andi Kleen <ak@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mempolicy: rename mpol_copy to mpol_dupLee Schermerhorn2008-04-28
| | | | | | | | | | | | | | | | | This patch renames mpol_copy() to mpol_dup() because, well, that's what it does. Like, e.g., strdup() for strings, mpol_dup() takes a pointer to an existing mempolicy, allocates a new one and copies the contents. In a later patch, I want to use the name mpol_copy() to copy the contents from one mempolicy to another like, e.g., strcpy() does for strings. Signed-off-by: Lee Schermerhorn <lee.schermerhorn@hp.com> Cc: Christoph Lameter <clameter@sgi.com> Cc: David Rientjes <rientjes@google.com> Cc: Mel Gorman <mel@csn.ul.ie> Cc: Andi Kleen <ak@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mempolicy: rename mpol_free to mpol_putLee Schermerhorn2008-04-28
| | | | | | | | | | | | | | | | | | | | | | | | | This is a change that was requested some time ago by Mel Gorman. Makes sense to me, so here it is. Note: I retain the name "mpol_free_shared_policy()" because it actually does free the shared_policy, which is NOT a reference counted object. However, ... The mempolicy object[s] referenced by the shared_policy are reference counted, so mpol_put() is used to release the reference held by the shared_policy. The mempolicy might not be freed at this time, because some task attached to the shared object associated with the shared policy may be in the process of allocating a page based on the mempolicy. In that case, the task performing the allocation will hold a reference on the mempolicy, obtained via mpol_shared_policy_lookup(). The mempolicy will be freed when all tasks holding such a reference have called mpol_put() for the mempolicy. Signed-off-by: Lee Schermerhorn <lee.schermerhorn@hp.com> Cc: Christoph Lameter <clameter@sgi.com> Cc: David Rientjes <rientjes@google.com> Cc: Mel Gorman <mel@csn.ul.ie> Cc: Andi Kleen <ak@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mempolicy: disallow static or relative flags for local preferred modeDavid Rientjes2008-04-28
| | | | | | | | | | | | | | | | | | | | | MPOL_F_STATIC_NODES and MPOL_F_RELATIVE_NODES don't mean anything for MPOL_PREFERRED policies that were created with an empty nodemask (for purely local allocations). They'll never be invalidated because the allowed mems of a task changes or need to be rebound relative to a cpuset's placement. Also fixes a bug identified by Lee Schermerhorn that disallowed empty nodemasks to be passed to MPOL_PREFERRED to specify local allocations. [A different, somewhat incomplete, patch already existed in 25-rc5-mm1.] Cc: Paul Jackson <pj@sgi.com> Cc: Christoph Lameter <clameter@sgi.com> Cc: Lee Schermerhorn <Lee.Schermerhorn@hp.com> Cc: Andi Kleen <ak@suse.de> Cc: Randy Dunlap <randy.dunlap@oracle.com> Signed-off-by: Lee Schermerhorn <lee.schermerhorn@hp.com> Signed-off-by: David Rientjes <rientjes@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mempolicy: create mempolicy_operations structureDavid Rientjes2008-04-28
| | | | | | | | | | | | | | | | | | | | | | | | | | Create a mempolicy_operations structure that currently points to two functions[*] for the various modes: int (*create)(struct mempolicy *, const nodemask_t *); void (*rebind)(struct mempolicy *, const nodemask_t *); This splits the implementation for the various modes out of two large functions, mpol_new() and mpol_rebind_policy(). Eventually it may be beneficial to add additional functions to accomodate the existing switch() statements in mm/mempolicy.c. [*] The ->create() function for MPOL_DEFAULT is currently NULL since no struct mempolicy is dynamically allocated. [Lee.Schermerhorn@hp.com: fix regression in the package mempolicy regression tests] Signed-off-by: David Rientjes <rientjes@google.com> Cc: Paul Jackson <pj@sgi.com> Cc: Christoph Lameter <clameter@sgi.com> Cc: Andi Kleen <ak@suse.de> Signed-off-by: Lee Schermerhorn <lee.schermerhorn@hp.com> Cc: Eric Whitney <eric.whitney@hp.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mempolicy: move rebind functionsDavid Rientjes2008-04-28
| | | | | | | | | | | | | Move the mpol_rebind_{policy,task,mm}() functions after mpol_new() to avoid having to declare function prototypes. Cc: Paul Jackson <pj@sgi.com> Cc: Christoph Lameter <clameter@sgi.com> Cc: Lee Schermerhorn <Lee.Schermerhorn@hp.com> Cc: Andi Kleen <ak@suse.de> Signed-off-by: David Rientjes <rientjes@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mempolicy: add MPOL_F_RELATIVE_NODES flagDavid Rientjes2008-04-28
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Adds another optional mode flag, MPOL_F_RELATIVE_NODES, that specifies nodemasks passed via set_mempolicy() or mbind() should be considered relative to the current task's mems_allowed. When the mempolicy is created, the passed nodemask is folded and mapped onto the current task's mems_allowed. For example, consider a task using set_mempolicy() to pass MPOL_INTERLEAVE | MPOL_F_RELATIVE_NODES with a nodemask of 1-3. If current's mems_allowed is 4-7, the effected nodemask is 5-7 (the second, third, and fourth node of mems_allowed). If the same task is attached to a cpuset, the mempolicy nodemask is rebound each time the mems are changed. Some possible rebinds and results are: mems result 1-3 1-3 1-7 2-4 1,5-6 1,5-6 1,5-7 5-7 Likewise, the zonelist built for MPOL_BIND acts on the set of zones assigned to the resultant nodemask from the relative remap. In the MPOL_PREFERRED case, the preferred node is remapped from the currently effected nodemask to the relative nodemask. This mempolicy mode flag was conceived of by Paul Jackson <pj@sgi.com>. Cc: Paul Jackson <pj@sgi.com> Cc: Christoph Lameter <clameter@sgi.com> Cc: Lee Schermerhorn <Lee.Schermerhorn@hp.com> Cc: Andi Kleen <ak@suse.de> Signed-off-by: David Rientjes <rientjes@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mempolicy: add MPOL_F_STATIC_NODES flagDavid Rientjes2008-04-28
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Add an optional mempolicy mode flag, MPOL_F_STATIC_NODES, that suppresses the node remap when the policy is rebound. Adds another member to struct mempolicy, nodemask_t user_nodemask, as part of a union with cpuset_mems_allowed: struct mempolicy { ... union { nodemask_t cpuset_mems_allowed; nodemask_t user_nodemask; } w; } that stores the the nodemask that the user passed when he or she created the mempolicy via set_mempolicy() or mbind(). When using MPOL_F_STATIC_NODES, which is passed with any mempolicy mode, the user's passed nodemask intersected with the VMA or task's allowed nodes is always used when determining the preferred node, setting the MPOL_BIND zonelist, or creating the interleave nodemask. This happens whenever the policy is rebound, including when a task's cpuset assignment changes or the cpuset's mems are changed. This creates an interesting side-effect in that it allows the mempolicy "intent" to lie dormant and uneffected until it has access to the node(s) that it desires. For example, if you currently ask for an interleaved policy over a set of nodes that you do not have access to, the mempolicy is not created and the task continues to use the previous policy. With this change, however, it is possible to create the same mempolicy; it is only effected when access to nodes in the nodemask is acquired. It is also possible to mount tmpfs with the static nodemask behavior when specifying a node or nodemask. To do this, simply add "=static" immediately following the mempolicy mode at mount time: mount -o remount mpol=interleave=static:1-3 Also removes mpol_check_policy() and folds its logic into mpol_new() since it is now obsoleted. The unused vma_mpol_equal() is also removed. Cc: Paul Jackson <pj@sgi.com> Cc: Christoph Lameter <clameter@sgi.com> Cc: Lee Schermerhorn <Lee.Schermerhorn@hp.com> Cc: Andi Kleen <ak@suse.de> Signed-off-by: David Rientjes <rientjes@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mempolicy: support optional mode flagsDavid Rientjes2008-04-28
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | With the evolution of mempolicies, it is necessary to support mempolicy mode flags that specify how the policy shall behave in certain circumstances. The most immediate need for mode flag support is to suppress remapping the nodemask of a policy at the time of rebind. Both the mempolicy mode and flags are passed by the user in the 'int policy' formal of either the set_mempolicy() or mbind() syscall. A new constant, MPOL_MODE_FLAGS, represents the union of legal optional flags that may be passed as part of this int. Mempolicies that include illegal flags as part of their policy are rejected as invalid. An additional member to struct mempolicy is added to support the mode flags: struct mempolicy { ... unsigned short policy; unsigned short flags; } The splitting of the 'int' actual passed by the user is done in sys_set_mempolicy() and sys_mbind() for their respective syscalls. This is done by intersecting the actual with MPOL_MODE_FLAGS, rejecting the syscall of there are additional flags, and storing it in the new 'flags' member of struct mempolicy. The intersection of the actual with ~MPOL_MODE_FLAGS is stored in the 'policy' member of the struct and all current users of pol->policy remain unchanged. The union of the policy mode and optional mode flags is passed back to the user in get_mempolicy(). This combination of mode and flags within the same actual does not break userspace code that relies on get_mempolicy(&policy, ...) and either switch (policy) { case MPOL_BIND: ... case MPOL_INTERLEAVE: ... }; statements or if (policy == MPOL_INTERLEAVE) { ... } statements. Such applications would need to use optional mode flags when calling set_mempolicy() or mbind() for these previously implemented statements to stop working. If an application does start using optional mode flags, it will need to mask the optional flags off the policy in switch and conditional statements that only test mode. An additional member is also added to struct shmem_sb_info to store the optional mode flags. [hugh@veritas.com: shmem mpol: fix build warning] Cc: Paul Jackson <pj@sgi.com> Cc: Christoph Lameter <clameter@sgi.com> Cc: Lee Schermerhorn <Lee.Schermerhorn@hp.com> Cc: Andi Kleen <ak@suse.de> Signed-off-by: David Rientjes <rientjes@google.com> Signed-off-by: Hugh Dickins <hugh@veritas.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mempolicy: convert MPOL constants to enumDavid Rientjes2008-04-28
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The mempolicy mode constants, MPOL_DEFAULT, MPOL_PREFERRED, MPOL_BIND, and MPOL_INTERLEAVE, are better declared as part of an enum since they are sequentially numbered and cannot be combined. The policy member of struct mempolicy is also converted from type short to type unsigned short. A negative policy does not have any legitimate meaning, so it is possible to change its type in preparation for adding optional mode flags later. The equivalent member of struct shmem_sb_info is also changed from int to unsigned short. For compatibility, the policy formal to get_mempolicy() remains as a pointer to an int: int get_mempolicy(int *policy, unsigned long *nmask, unsigned long maxnode, unsigned long addr, unsigned long flags); although the only possible values is the range of type unsigned short. Cc: Paul Jackson <pj@sgi.com> Cc: Christoph Lameter <clameter@sgi.com> Cc: Lee Schermerhorn <Lee.Schermerhorn@hp.com> Cc: Andi Kleen <ak@suse.de> Signed-off-by: David Rientjes <rientjes@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: filter based on a nodemask as well as a gfp_maskMel Gorman2008-04-28
| | | | | | | | | | | | | | | | | | | | | | | | | | The MPOL_BIND policy creates a zonelist that is used for allocations controlled by that mempolicy. As the per-node zonelist is already being filtered based on a zone id, this patch adds a version of __alloc_pages() that takes a nodemask for further filtering. This eliminates the need for MPOL_BIND to create a custom zonelist. A positive benefit of this is that allocations using MPOL_BIND now use the local node's distance-ordered zonelist instead of a custom node-id-ordered zonelist. I.e., pages will be allocated from the closest allowed node with available memory. [Lee.Schermerhorn@hp.com: Mempolicy: update stale documentation and comments] [Lee.Schermerhorn@hp.com: Mempolicy: make dequeue_huge_page_vma() obey MPOL_BIND nodemask] [Lee.Schermerhorn@hp.com: Mempolicy: make dequeue_huge_page_vma() obey MPOL_BIND nodemask rework] Signed-off-by: Mel Gorman <mel@csn.ul.ie> Acked-by: Christoph Lameter <clameter@sgi.com> Signed-off-by: Lee Schermerhorn <lee.schermerhorn@hp.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Mel Gorman <mel@csn.ul.ie> Cc: Hugh Dickins <hugh@veritas.com> Cc: Nick Piggin <nickpiggin@yahoo.com.au> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: have zonelist contains structs with both a zone pointer and zone_idxMel Gorman2008-04-28
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Filtering zonelists requires very frequent use of zone_idx(). This is costly as it involves a lookup of another structure and a substraction operation. As the zone_idx is often required, it should be quickly accessible. The node idx could also be stored here if it was found that accessing zone->node is significant which may be the case on workloads where nodemasks are heavily used. This patch introduces a struct zoneref to store a zone pointer and a zone index. The zonelist then consists of an array of these struct zonerefs which are looked up as necessary. Helpers are given for accessing the zone index as well as the node index. [kamezawa.hiroyu@jp.fujitsu.com: Suggested struct zoneref instead of embedding information in pointers] [hugh@veritas.com: mm-have-zonelist: fix memcg ooms] [hugh@veritas.com: just return do_try_to_free_pages] [hugh@veritas.com: do_try_to_free_pages gfp_mask redundant] Signed-off-by: Mel Gorman <mel@csn.ul.ie> Acked-by: Christoph Lameter <clameter@sgi.com> Acked-by: David Rientjes <rientjes@google.com> Signed-off-by: Lee Schermerhorn <lee.schermerhorn@hp.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Mel Gorman <mel@csn.ul.ie> Cc: Christoph Lameter <clameter@sgi.com> Cc: Nick Piggin <nickpiggin@yahoo.com.au> Signed-off-by: Hugh Dickins <hugh@veritas.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: introduce node_zonelist() for accessing the zonelist for a GFP maskMel Gorman2008-04-28
| | | | | | | | | | | | | | | | | | Introduce a node_zonelist() helper function. It is used to lookup the appropriate zonelist given a node and a GFP mask. The patch on its own is a cleanup but it helps clarify parts of the two-zonelist-per-node patchset. If necessary, it can be merged with the next patch in this set without problems. Reviewed-by: Christoph Lameter <clameter@sgi.com> Signed-off-by: Mel Gorman <mel@csn.ul.ie> Signed-off-by: Lee Schermerhorn <lee.schermerhorn@hp.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Mel Gorman <mel@csn.ul.ie> Cc: Christoph Lameter <clameter@sgi.com> Cc: Hugh Dickins <hugh@veritas.com> Cc: Nick Piggin <nickpiggin@yahoo.com.au> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mempolicy: fix reference counting bugsLee Schermerhorn2008-03-10
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Address 3 known bugs in the current memory policy reference counting method. I have a series of patches to rework the reference counting to reduce overhead in the allocation path. However, that series will require testing in -mm once I repost it. 1) alloc_page_vma() does not release the extra reference taken for vma/shared mempolicy when the mode == MPOL_INTERLEAVE. This can result in leaking mempolicy structures. This is probably occurring, but not being noticed. Fix: add the conditional release of the reference. 2) hugezonelist unconditionally releases a reference on the mempolicy when mode == MPOL_INTERLEAVE. This can result in decrementing the reference count for system default policy [should have no ill effect] or premature freeing of task policy. If this occurred, the next allocation using task mempolicy would use the freed structure and probably BUG out. Fix: add the necessary check to the release. 3) The current reference counting method assumes that vma 'get_policy()' methods automatically add an extra reference a non-NULL returned mempolicy. This is true for shmem_get_policy() used by tmpfs mappings, including regular page shm segments. However, SHM_HUGETLB shm's, backed by hugetlbfs, just use the vma policy without the extra reference. This results in freeing of the vma policy on the first allocation, with reuse of the freed mempolicy structure on subsequent allocations. Fix: Rather than add another condition to the conditional reference release, which occur in the allocation path, just add a reference when returning the vma policy in shm_get_policy() to match the assumptions. Signed-off-by: Lee Schermerhorn <lee.schermerhorn@hp.com> Cc: Greg KH <greg@kroah.com> Cc: Andi Kleen <ak@suse.de> Cc: Christoph Lameter <clameter@sgi.com> Cc: Mel Gorman <mel@csn.ul.ie> Cc: David Rientjes <rientjes@google.com> Cc: <eric.whitney@hp.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* d_path: Make seq_path() use a struct path argumentJan Blunck2008-02-15
| | | | | | | | | | | | | seq_path() is always called with a dentry and a vfsmount from a struct path. Make seq_path() take it directly as an argument. Signed-off-by: Jan Blunck <jblunck@suse.de> Cc: Christoph Hellwig <hch@lst.de> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: "J. Bruce Fields" <bfields@fieldses.org> Cc: Neil Brown <neilb@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mempolicy: silently restrict nodemask to allowed nodesKOSAKI Motohiro2008-02-11
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Kosaki Motohito noted that "numactl --interleave=all ..." failed in the presence of memoryless nodes. This patch attempts to fix that problem. Some background: numactl --interleave=all calls set_mempolicy(2) with a fully populated [out to MAXNUMNODES] nodemask. set_mempolicy() [in do_set_mempolicy()] calls contextualize_policy() which requires that the nodemask be a subset of the current task's mems_allowed; else EINVAL will be returned. A task's mems_allowed will always be a subset of node_states[N_HIGH_MEMORY] i.e., nodes with memory. So, a fully populated nodemask will be declared invalid if it includes memoryless nodes. NOTE: the same thing will occur when running in a cpuset with restricted mem_allowed--for the same reason: node mask contains dis-allowed nodes. mbind(2), on the other hand, just masks off any nodes in the nodemask that are not included in the caller's mems_allowed. In each case [mbind() and set_mempolicy()], mpol_check_policy() will complain [again, resulting in EINVAL] if the nodemask contains any memoryless nodes. This is somewhat redundant as mpol_new() will remove memoryless nodes for interleave policy, as will bind_zonelist()--called by mpol_new() for BIND policy. Proposed fix: 1) modify contextualize_policy logic to: a) remember whether the incoming node mask is empty. b) if not, restrict the nodemask to allowed nodes, as is currently done in-line for mbind(). This guarantees that the resulting mask includes only nodes with memory. NOTE: this is a [benign, IMO] change in behavior for set_mempolicy(). Dis-allowed nodes will be silently ignored, rather than returning an error. c) fold this code into mpol_check_policy(), replace 2 calls to contextualize_policy() to call mpol_check_policy() directly and remove contextualize_policy(). 2) In existing mpol_check_policy() logic, after "contextualization": a) MPOL_DEFAULT: require that in coming mask "was_empty" b) MPOL_{BIND|INTERLEAVE}: require that contextualized nodemask contains at least one node. c) add a case for MPOL_PREFERRED: if in coming was not empty and resulting mask IS empty, user specified invalid nodes. Return EINVAL. c) remove the now redundant check for memoryless nodes 3) remove the now redundant masking of policy nodes for interleave policy from mpol_new(). 4) Now that mpol_check_policy() contextualizes the nodemask, remove the in-line nodes_and() from sys_mbind(). I believe that this restores mbind() to the behavior before the memoryless-nodes patch series. E.g., we'll no longer treat an invalid nodemask with MPOL_PREFERRED as local allocation. [ Patch history: v1 -> v2: - Communicate whether or not incoming node mask was empty to mpol_check_policy() for better error checking. - As suggested by David Rientjes, remove the now unused cpuset_nodes_subset_current_mems_allowed() from cpuset.h v2 -> v3: - As suggested by Kosaki Motohito, fold the "contextualization" of policy nodemask into mpol_check_policy(). Looks a little cleaner. ] Signed-off-by: Lee Schermerhorn <lee.schermerhorn@hp.com> Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Tested-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Acked-by: David Rientjes <rientjes@google.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* Migration: find correct vma in new_vma_page()Lee Schermerhorn2007-11-14
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | We hit the BUG_ON() in mm/rmap.c:vma_address() when trying to migrate via mbind(MPOL_MF_MOVE) a non-anon region that spans multiple vmas. For anon-regions, we just fail to migrate any pages beyond the 1st vma in the range. This occurs because do_mbind() collects a list of pages to migrate by calling check_range(). check_range() walks the task's mm, spanning vmas as necessary, to collect the migratable pages into a list. Then, do_mbind() calls migrate_pages() passing the list of pages, a function to allocate new pages based on vma policy [new_vma_page()], and a pointer to the first vma of the range. For each page in the list, new_vma_page() calls page_address_in_vma() passing the page and the vma [first in range] to obtain the address to get for alloc_page_vma(). The page address is needed to get interleaving policy correct. If the pages in the list come from multiple vmas, eventually, new_page_address() will pass that page to page_address_in_vma() with the incorrect vma. For !PageAnon pages, this will result in a bug check in rmap.c:vma_address(). For anon pages, vma_address() will just return EFAULT and fail the migration. This patch modifies new_vma_page() to check the return value from page_address_in_vma(). If the return value is EFAULT, new_vma_page() searchs forward via vm_next for the vma that maps the page--i.e., that does not return EFAULT. This assumes that the pages in the list handed to migrate_pages() is in address order. This is currently case. The patch documents this assumption in a new comment block for new_vma_page(). If new_vma_page() cannot locate the vma mapping the page in a forward search in the mm, it will pass a NULL vma to alloc_page_vma(). This will result in the allocation using the task policy, if any, else system default policy. This situation is unlikely, but the patch documents this behavior with a comment. Note, this patch results in restarting from the first vma in a multi-vma range each time new_vma_page() is called. If this is not acceptable, we can make the vma argument a pointer, both in new_vma_page() and it's caller unmap_and_move() so that the value held by the loop in migrate_pages() always passes down the last vma in which a page was found. This will require changes to all new_page_t functions passed to migrate_pages(). Is this necessary? For this patch to work, we can't bug check in vma_address() for pages outside the argument vma. This patch removes the BUG_ON(). All other callers [besides new_vma_page()] already check the return status. Tested on x86_64, 4 node NUMA platform. Signed-off-by: Lee Schermerhorn <lee.schermerhorn@hp.com> Acked-by: Christoph Lameter <clameter@sgi.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* Uninline find_task_by_xxx set of functionsPavel Emelyanov2007-10-19
| | | | | | | | | | | | | | | | | | | | | | | | The find_task_by_something is a set of macros are used to find task by pid depending on what kind of pid is proposed - global or virtual one. All of them are wrappers above the most generic one - find_task_by_pid_type_ns() - and just substitute some args for it. It turned out, that dereferencing the current->nsproxy->pid_ns construction and pushing one more argument on the stack inline cause kernel text size to grow. This patch moves all this stuff out-of-line into kernel/pid.c. Together with the next patch it saves a bit less than 400 bytes from the .text section. Signed-off-by: Pavel Emelyanov <xemul@openvz.org> Cc: Sukadev Bhattiprolu <sukadev@us.ibm.com> Cc: Oleg Nesterov <oleg@tv-sign.ru> Cc: Paul Menage <menage@google.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Acked-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* pid namespaces: changes to show virtual ids to userPavel Emelyanov2007-10-19
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | This is the largest patch in the set. Make all (I hope) the places where the pid is shown to or get from user operate on the virtual pids. The idea is: - all in-kernel data structures must store either struct pid itself or the pid's global nr, obtained with pid_nr() call; - when seeking the task from kernel code with the stored id one should use find_task_by_pid() call that works with global pids; - when showing pid's numerical value to the user the virtual one should be used, but however when one shows task's pid outside this task's namespace the global one is to be used; - when getting the pid from userspace one need to consider this as the virtual one and use appropriate task/pid-searching functions. [akpm@linux-foundation.org: build fix] [akpm@linux-foundation.org: nuther build fix] [akpm@linux-foundation.org: yet nuther build fix] [akpm@linux-foundation.org: remove unneeded casts] Signed-off-by: Pavel Emelyanov <xemul@openvz.org> Signed-off-by: Alexey Dobriyan <adobriyan@openvz.org> Cc: Sukadev Bhattiprolu <sukadev@us.ibm.com> Cc: Oleg Nesterov <oleg@tv-sign.ru> Cc: Paul Menage <menage@google.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* Task Control Groups: make cpusets a client of cgroupsPaul Menage2007-10-19
| | | | | | | | | | | | | | | | | | | | | | Remove the filesystem support logic from the cpusets system and makes cpusets a cgroup subsystem The "cpuset" filesystem becomes a dummy filesystem; attempts to mount it get passed through to the cgroup filesystem with the appropriate options to emulate the old cpuset filesystem behaviour. Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm/mempolicy.c: cleanupsAdrian Bunk2007-10-16
| | | | | | | | | | | | | | | | | This patch contains the following cleanups: - every file should include the headers containing the prototypes for its global functions - make the follosing needlessly global functions static: - migrate_to_node() - do_mbind() - sp_alloc() - mpol_rebind_policy() [akpm@linux-foundation.org: fix uninitialised var warning] Signed-off-by: Adrian Bunk <bunk@stusta.de> Acked-by: Christoph Lameter <clameter@sgi.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* memoryless nodes: fixup uses of node_online_map in generic codeLee Schermerhorn2007-10-16
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Here's a cut at fixing up uses of the online node map in generic code. mm/shmem.c:shmem_parse_mpol() Ensure nodelist is subset of nodes with memory. Use node_states[N_HIGH_MEMORY] as default for missing nodelist for interleave policy. mm/shmem.c:shmem_fill_super() initialize policy_nodes to node_states[N_HIGH_MEMORY] mm/page-writeback.c:highmem_dirtyable_memory() sum over nodes with memory mm/page_alloc.c:zlc_setup() allowednodes - use nodes with memory. mm/page_alloc.c:default_zonelist_order() average over nodes with memory. mm/page_alloc.c:find_next_best_node() skip nodes w/o memory. N_HIGH_MEMORY state mask may not be initialized at this time, unless we want to depend on early_calculate_totalpages() [see below]. Will ZONE_MOVABLE ever be configurable? mm/page_alloc.c:find_zone_movable_pfns_for_nodes() spread kernelcore over nodes with memory. This required calling early_calculate_totalpages() unconditionally, and populating N_HIGH_MEMORY node state therein from nodes in the early_node_map[]. If we can depend on this, we can eliminate the population of N_HIGH_MEMORY mask from __build_all_zonelists() and use the N_HIGH_MEMORY mask in find_next_best_node(). mm/mempolicy.c:mpol_check_policy() Ensure nodes specified for policy are subset of nodes with memory. [akpm@linux-foundation.org: fix warnings] Signed-off-by: Lee Schermerhorn <lee.schermerhorn@hp.com> Acked-by: Christoph Lameter <clameter@sgi.com> Cc: Shaohua Li <shaohua.li@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* Memoryless nodes: Update memory policy and page migrationChristoph Lameter2007-10-16
| | | | | | | | | | | | | | | | | | | | | | | | | Online nodes now may have no memory. The checks and initialization must therefore be changed to no longer use the online functions. This will correctly initialize the interleave on bootup to only target nodes with memory and will make sys_move_pages return an error when a page is to be moved to a memoryless node. Similarly we will get an error if MPOL_BIND and MPOL_INTERLEAVE is used on a memoryless node. These are somewhat new semantics. So far one could specify memoryless nodes and we would maybe do the right thing and just ignore the node (or we'd do something strange like with MPOL_INTERLEAVE). If we want to allow the specification of memoryless nodes via memory policies then we need to keep checking for online nodes. Signed-off-by: Christoph Lameter <clameter@sgi.com> Acked-by: Nishanth Aravamudan <nacc@us.ibm.com> Tested-by: Lee Schermerhorn <lee.schermerhorn@hp.com> Acked-by: Bob Picco <bob.picco@hp.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Mel Gorman <mel@skynet.ie> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* Memoryless nodes: Fix interleave behavior for memoryless nodesChristoph Lameter2007-10-16
| | | | | | | | | | | | | | | | | | | | MPOL_INTERLEAVE currently simply loops over all nodes. Allocations on memoryless nodes will be redirected to nodes with memory. This results in an imbalance because the neighboring nodes to memoryless nodes will get significantly more interleave hits that the rest of the nodes on the system. We can avoid this imbalance by clearing the nodes in the interleave node set that have no memory. If we use the node map of the memory nodes instead of the online nodes then we have only the nodes we want. Signed-off-by: Christoph Lameter <clameter@sgi.com> Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com> Tested-by: Lee Schermerhorn <lee.schermerhorn@hp.com> Acked-by: Bob Picco <bob.picco@hp.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Mel Gorman <mel@skynet.ie> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* Mem Policy: add MPOL_F_MEMS_ALLOWED get_mempolicy() flagLee Schermerhorn2007-10-16
| | | | | | | | | | | | | | | | | | | | Allow an application to query the memories allowed by its context. Updated numa_memory_policy.txt to mention that applications can use this to obtain allowed memories for constructing valid policies. TODO: update out-of-tree libnuma wrapper[s], or maybe add a new wrapper--e.g., numa_get_mems_allowed() ? Also, update numa syscall man pages. Tested with memtoy V>=0.13. Signed-off-by: Lee Schermerhorn <lee.schermerhorn@hp.com> Acked-by: Christoph Lameter <clameter@sgi.com> Cc: Andi Kleen <ak@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* Clean up duplicate includes in mm/Jesper Juhl2007-10-16
| | | | | | | | | | This patch cleans up duplicate includes in mm/ Signed-off-by: Jesper Juhl <jesper.juhl@gmail.com> Acked-by: Paul Mundt <lethal@linux-sh.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* Fix NUMA Memory Policy Reference CountingLee Schermerhorn2007-09-19
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This patch proposes fixes to the reference counting of memory policy in the page allocation paths and in show_numa_map(). Extracted from my "Memory Policy Cleanups and Enhancements" series as stand-alone. Shared policy lookup [shmem] has always added a reference to the policy, but this was never unrefed after page allocation or after formatting the numa map data. Default system policy should not require additional ref counting, nor should the current task's task policy. However, show_numa_map() calls get_vma_policy() to examine what may be [likely is] another task's policy. The latter case needs protection against freeing of the policy. This patch adds a reference count to a mempolicy returned by get_vma_policy() when the policy is a vma policy or another task's mempolicy. Again, shared policy is already reference counted on lookup. A matching "unref" [__mpol_free()] is performed in alloc_page_vma() for shared and vma policies, and in show_numa_map() for shared and another task's mempolicy. We can call __mpol_free() directly, saving an admittedly inexpensive inline NULL test, because we know we have a non-NULL policy. Handling policy ref counts for hugepages is a bit trickier. huge_zonelist() returns a zone list that might come from a shared or vma 'BIND policy. In this case, we should hold the reference until after the huge page allocation in dequeue_hugepage(). The patch modifies huge_zonelist() to return a pointer to the mempolicy if it needs to be unref'd after allocation. Kernel Build [16cpu, 32GB, ia64] - average of 10 runs: w/o patch w/ refcount patch Avg Std Devn Avg Std Devn Real: 100.59 0.38 100.63 0.43 User: 1209.60 0.37 1209.91 0.31 System: 81.52 0.42 81.64 0.34 Signed-off-by: Lee Schermerhorn <lee.schermerhorn@hp.com> Acked-by: Andi Kleen <ak@suse.de> Cc: Christoph Lameter <clameter@sgi.com> Acked-by: Mel Gorman <mel@csn.ul.ie> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* Page migration: Do not accept invalid nodes in the target nodesetChristoph Lameter2007-08-31
| | | | | | | | | | | | | | Page migration currently does not check if the target of the move contains nodes that that are invalid (if root attempts to migrate pages) and may try to allocate from invalid nodes if these are specified leading to oopses. Return -EINVAL if an offline node is specified. Signed-off-by: Christoph Lameter <clameter@sgi.com> Cc: Shaohua Li <shaohua.li@intel.com> Cc: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* Apply memory policies to top two highest zones when highest zone is ZONE_MOVABLEMel Gorman2007-08-22
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The NUMA layer only supports NUMA policies for the highest zone. When ZONE_MOVABLE is configured with kernelcore=, the the highest zone becomes ZONE_MOVABLE. The result is that policies are only applied to allocations like anonymous pages and page cache allocated from ZONE_MOVABLE when the zone is used. This patch applies policies to the two highest zones when the highest zone is ZONE_MOVABLE. As ZONE_MOVABLE consists of pages from the highest "real" zone, it's always functionally equivalent. The patch has been tested on a variety of machines both NUMA and non-NUMA covering x86, x86_64 and ppc64. No abnormal results were seen in kernbench, tbench, dbench or hackbench. It passes regression tests from the numactl package with and without kernelcore= once numactl tests are patched to wait for vmstat counters to update. akpm: this is the nasty hack to fix NUMA mempolicies in the presence of ZONE_MOVABLE and kernelcore= in 2.6.23. Christoph says "For .24 either merge the mobility or get the other solution that Mel is working on. That solution would only use a single zonelist per node and filter on the fly. That may help performance and also help to make memory policies work better." Signed-off-by: Mel Gorman <mel@csn.ul.ie> Acked-by: Lee Schermerhorn <lee.schermerhorn@hp.com> Tested-by: Lee Schermerhorn <lee.schermerhorn@hp.com> Acked-by: Christoph Lameter <clameter@sgi.com> Cc: Andi Kleen <ak@suse.de> Cc: Paul Mundt <lethal@linux-sh.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: Remove slab destructors from kmem_cache_create().Paul Mundt2007-07-19
| | | | | | | | | | | | | | Slab destructors were no longer supported after Christoph's c59def9f222d44bb7e2f0a559f2906191a0862d7 change. They've been BUGs for both slab and slub, and slob never supported them either. This rips out support for the dtor pointer from kmem_cache_create() completely and fixes up every single callsite in the kernel (there were about 224, not including the slab allocator definitions themselves, or the documentation references). Signed-off-by: Paul Mundt <lethal@linux-sh.org>
* Allow huge page allocations to use GFP_HIGH_MOVABLEMel Gorman2007-07-17
| | | | | | | | | | | | | | | | | | | Huge pages are not movable so are not allocated from ZONE_MOVABLE. However, as ZONE_MOVABLE will always have pages that can be migrated or reclaimed, it can be used to satisfy hugepage allocations even when the system has been running a long time. This allows an administrator to resize the hugepage pool at runtime depending on the size of ZONE_MOVABLE. This patch adds a new sysctl called hugepages_treat_as_movable. When a non-zero value is written to it, future allocations for the huge page pool will use ZONE_MOVABLE. Despite huge pages being non-movable, we do not introduce additional external fragmentation of note as huge pages are always the largest contiguous block we care about. [akpm@linux-foundation.org: various fixes] Signed-off-by: Mel Gorman <mel@csn.ul.ie> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* Add __GFP_MOVABLE for callers to flag allocations from high memory that may ↵Mel Gorman2007-07-17
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | be migrated It is often known at allocation time whether a page may be migrated or not. This patch adds a flag called __GFP_MOVABLE and a new mask called GFP_HIGH_MOVABLE. Allocations using the __GFP_MOVABLE can be either migrated using the page migration mechanism or reclaimed by syncing with backing storage and discarding. An API function very similar to alloc_zeroed_user_highpage() is added for __GFP_MOVABLE allocations called alloc_zeroed_user_highpage_movable(). The flags used by alloc_zeroed_user_highpage() are not changed because it would change the semantics of an existing API. After this patch is applied there are no in-kernel users of alloc_zeroed_user_highpage() so it probably should be marked deprecated if this patch is merged. Note that this patch includes a minor cleanup to the use of __GFP_ZERO in shmem.c to keep all flag modifications to inode->mapping in the shmem_dir_alloc() helper function. This clean-up suggestion is courtesy of Hugh Dickens. Additional credit goes to Christoph Lameter and Linus Torvalds for shaping the concept. Credit to Hugh Dickens for catching issues with shmem swap vector and ramfs allocations. [akpm@linux-foundation.org: build fix] [hugh@veritas.com: __GFP_ZERO cleanup] Signed-off-by: Mel Gorman <mel@csn.ul.ie> Cc: Andy Whitcroft <apw@shadowen.org> Cc: Christoph Lameter <clameter@sgi.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* numa: mempolicy: trivial debug fixes.Paul Mundt2007-07-16
| | | | | | | | | | | | | | | | Enabling debugging fails to build due to the nodemask variable in do_mbind() having changed names, and then oopses on boot due to the assumption that the nodemask can be dereferenced -- which doesn't work out so well when the policy is changed to MPOL_DEFAULT with a NULL nodemask by numa_default_policy(). This fixes it up, and switches from PDprintk() to pr_debug() while we're at it. Signed-off-by: Paul Mundt <lethal@linux-sh.org> Cc: Christoph Lameter <clameter@sgi.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* numa: mempolicy: dynamic interleave map for system initPaul Mundt2007-07-16
| | | | | | | | | | | | | | | | | | | | | | | This converts the default system init memory policy to use a dynamically created node map instead of defaulting to all online nodes. Nodes of a certain size (>= 16MB) are judged to be suitable for interleave, and are added to the map. If all nodes are smaller in size, the largest one is automatically selected. Without this, tiny nodes find themselves out of memory before we even make it to userspace. Systems with large nodes will notice no change. Only the system init policy is effected by this change, the regular MPOL_DEFAULT policy is still switched to later on in the boot process as normal. Signed-off-by: Paul Mundt <lethal@linux-sh.org> Cc: Andi Kleen <ak@suse.de> Cc: Christoph Lameter <clameter@sgi.com> Cc: Hugh Dickins <hugh@veritas.com> Cc: Lee Schermerhorn <lee.schermerhorn@hp.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* [PATCH] Page migration: Fix vma flag checkingChristoph Lameter2007-03-05
| | | | | | | | | | | | | | | | | Currently we do not check for vma flags if sys_move_pages is called to move individual pages. If sys_migrate_pages is called to move pages then we check for vm_flags that indicate a non migratable vma but that still includes VM_LOCKED and we can migrate mlocked pages. Extract the vma_migratable check from mm/mempolicy.c, fix it and put it into migrate.h so that is can be used from both locations. Problem was spotted by Lee Schermerhorn Signed-off-by: Christoph Lameter <clameter@sgi.com> Signed-off-by: Lee Schermerhorn <lee.schermerhorn@hp.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* [PATCH] fix mempolicy's check on a system with memory-less-nodeKAMEZAWA Hiroyuki2007-02-20
| | | | | | | | | | | | | | bind_zonelist() can create zero-length zonelist if there is a memory-less-node. This patch checks the length of zonelist. If length is 0, returns -EINVAL. tested on ia64/NUMA with memory-less-node. Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Acked-by: Andi Kleen <ak@suse.de> Cc: Christoph Lameter <clameter@sgi.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* [PATCH] optional ZONE_DMA: deal with cases of ZONE_DMA meaning the first zoneChristoph Lameter2007-02-11
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This patchset follows up on the earlier work in Andrew's tree to reduce the number of zones. The patches allow to go to a minimum of 2 zones. This one allows also to make ZONE_DMA optional and therefore the number of zones can be reduced to one. ZONE_DMA is usually used for ISA DMA devices. There are a number of reasons why we would not want to have ZONE_DMA 1. Some arches do not need ZONE_DMA at all. 2. With the advent of IOMMUs DMA zones are no longer needed. The necessity of DMA zones may drastically be reduced in the future. This patchset allows a compilation of a kernel without that overhead. 3. Devices that require ISA DMA get rare these days. All my systems do not have any need for ISA DMA. 4. The presence of an additional zone unecessarily complicates VM operations because it must be scanned and balancing logic must operate on its. 5. With only ZONE_NORMAL one can reach the situation where we have only one zone. This will allow the unrolling of many loops in the VM and allows the optimization of varous code paths in the VM. 6. Having only a single zone in a NUMA system results in a 1-1 correspondence between nodes and zones. Various additional optimizations to critical VM paths become possible. Many systems today can operate just fine with a single zone. If you look at what is in ZONE_DMA then one usually sees that nothing uses it. The DMA slabs are empty (Some arches use ZONE_DMA instead of ZONE_NORMAL, then ZONE_NORMAL will be empty instead). On all of my systems (i386, x86_64, ia64) ZONE_DMA is completely empty. Why constantly look at an empty zone in /proc/zoneinfo and empty slab in /proc/slabinfo? Non i386 also frequently have no need for ZONE_DMA and zones stay empty. The patchset was tested on i386 (UP / SMP), x86_64 (UP, NUMA) and ia64 (NUMA). The RFC posted earlier (see http://marc.theaimsgroup.com/?l=linux-kernel&m=115231723513008&w=2) had lots of #ifdefs in them. An effort has been made to minize the number of #ifdefs and make this as compact as possible. The job was made much easier by the ongoing efforts of others to extract common arch specific functionality. I have been running this for awhile now on my desktop and finally Linux is using all my available RAM instead of leaving the 16MB in ZONE_DMA untouched: christoph@pentium940:~$ cat /proc/zoneinfo Node 0, zone Normal pages free 4435 min 1448 low 1810 high 2172 active 241786 inactive 210170 scanned 0 (a: 0 i: 0) spanned 524224 present 524224 nr_anon_pages 61680 nr_mapped 14271 nr_file_pages 390264 nr_slab_reclaimable 27564 nr_slab_unreclaimable 1793 nr_page_table_pages 449 nr_dirty 39 nr_writeback 0 nr_unstable 0 nr_bounce 0 cpu: 0 pcp: 0 count: 156 high: 186 batch: 31 cpu: 0 pcp: 1 count: 9 high: 62 batch: 15 vm stats threshold: 20 cpu: 1 pcp: 0 count: 177 high: 186 batch: 31 cpu: 1 pcp: 1 count: 12 high: 62 batch: 15 vm stats threshold: 20 all_unreclaimable: 0 prev_priority: 12 temp_priority: 12 start_pfn: 0 This patch: In two places in the VM we use ZONE_DMA to refer to the first zone. If ZONE_DMA is optional then other zones may be first. So simply replace ZONE_DMA with zone 0. This also fixes ZONETABLE_PGSHIFT. If we have only a single zone then ZONES_PGSHIFT may become 0 because there is no need anymore to encode the zone number related to a pgdat. However, we still need a zonetable to index all the zones for each node if this is a NUMA system. Therefore define ZONETABLE_SHIFT unconditionally as the offset of the ZONE field in page flags. [apw@shadowen.org: fix mismerge] Acked-by: Christoph Hellwig <hch@infradead.org> Signed-off-by: Christoph Lameter <clameter@sgi.com> Cc: Andi Kleen <ak@suse.de> Cc: "Luck, Tony" <tony.luck@intel.com> Cc: Kyle McMartin <kyle@mcmartin.ca> Cc: Matthew Wilcox <willy@debian.org> Cc: James Bottomley <James.Bottomley@steeleye.com> Cc: Paul Mundt <lethal@linux-sh.org> Signed-off-by: Andy Whitcroft <apw@shadowen.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* [PATCH] mbind: restrict nodes to the currently allowed cpusetChristoph Lameter2007-01-23
| | | | | | | | | | | | | | | | | | | Currently one can specify an arbitrary node mask to mbind that includes nodes not allowed. If that is done with an interleave policy then we will go around all the nodes. Those outside of the currently allowed cpuset will be redirected to the border nodes. Interleave will then create imbalances at the borders of the cpuset. This patch restricts the nodes to the currently allowed cpuset. The RFC for this patch was discussed at http://marc.theaimsgroup.com/?t=116793842100004&r=1&w=2 Signed-off-by: Christoph Lameter <clameter@sgi.com> Cc: Paul Jackson <pj@sgi.com> Cc: Andi Kleen <ak@suse.de> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* [PATCH] struct path: convert mmJosef Sipek2006-12-08
| | | | | | Signed-off-by: Josef Sipek <jsipek@fsl.cs.sunysb.edu> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] struct seq_operations and struct file_operations constificationHelge Deller2006-12-07
| | | | | | | | | | | | | | - move some file_operations structs into the .rodata section - move static strings from policy_types[] array into the .rodata section - fix generic seq_operations usages, so that those structs may be defined as "const" as well [akpm@osdl.org: couple of fixes] Signed-off-by: Helge Deller <deller@gmx.de> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] slab: remove SLAB_KERNELChristoph Lameter2006-12-07
| | | | | | | | SLAB_KERNEL is an alias of GFP_KERNEL. Signed-off-by: Christoph Lameter <clameter@sgi.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] numa node ids are int, page_to_nid and zone_to_nid should return intAndy Whitcroft2006-12-07
| | | | | | | | | | | | | | | | | | | | | | | NUMA node ids are passed as either int or unsigned int almost exclusivly page_to_nid and zone_to_nid both return unsigned long. This is a throw back to when page_to_nid was a #define and was thus exposing the real type of the page flags field. In addition to fixing up the definitions of page_to_nid and zone_to_nid I audited the users of these functions identifying the following incorrect uses: 1) mm/page_alloc.c show_node() -- printk dumping the node id, 2) include/asm-ia64/pgalloc.h pgtable_quicklist_free() -- comparison against numa_node_id() which returns an int from cpu_to_node(), and 3) mm/mpolicy.c check_pte_range -- used as an index in node_isset which uses bit_set which in generic code takes an int. Signed-off-by: Andy Whitcroft <apw@shadowen.org> Cc: Christoph Lameter <clameter@engr.sgi.com> Cc: "Luck, Tony" <tony.luck@intel.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] memory page_alloc zonelist caching speedupPaul Jackson2006-12-07
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Optimize the critical zonelist scanning for free pages in the kernel memory allocator by caching the zones that were found to be full recently, and skipping them. Remembers the zones in a zonelist that were short of free memory in the last second. And it stashes a zone-to-node table in the zonelist struct, to optimize that conversion (minimize its cache footprint.) Recent changes: This differs in a significant way from a similar patch that I posted a week ago. Now, instead of having a nodemask_t of recently full nodes, I have a bitmask of recently full zones. This solves a problem that last weeks patch had, which on systems with multiple zones per node (such as DMA zone) would take seeing any of these zones full as meaning that all zones on that node were full. Also I changed names - from "zonelist faster" to "zonelist cache", as that seemed to better convey what we're doing here - caching some of the key zonelist state (for faster access.) See below for some performance benchmark results. After all that discussion with David on why I didn't need them, I went and got some ;). I wanted to verify that I had not hurt the normal case of memory allocation noticeably. At least for my one little microbenchmark, I found (1) the normal case wasn't affected, and (2) workloads that forced scanning across multiple nodes for memory improved up to 10% fewer System CPU cycles and lower elapsed clock time ('sys' and 'real'). Good. See details, below. I didn't have the logic in get_page_from_freelist() for various full nodes and zone reclaim failures correct. That should be fixed up now - notice the new goto labels zonelist_scan, this_zone_full, and try_next_zone, in get_page_from_freelist(). There are two reasons I persued this alternative, over some earlier proposals that would have focused on optimizing the fake numa emulation case by caching the last useful zone: 1) Contrary to what I said before, we (SGI, on large ia64 sn2 systems) have seen real customer loads where the cost to scan the zonelist was a problem, due to many nodes being full of memory before we got to a node we could use. Or at least, I think we have. This was related to me by another engineer, based on experiences from some time past. So this is not guaranteed. Most likely, though. The following approach should help such real numa systems just as much as it helps fake numa systems, or any combination thereof. 2) The effort to distinguish fake from real numa, using node_distance, so that we could cache a fake numa node and optimize choosing it over equivalent distance fake nodes, while continuing to properly scan all real nodes in distance order, was going to require a nasty blob of zonelist and node distance munging. The following approach has no new dependency on node distances or zone sorting. See comment in the patch below for a description of what it actually does. Technical details of note (or controversy): - See the use of "zlc_active" and "did_zlc_setup" below, to delay adding any work for this new mechanism until we've looked at the first zone in zonelist. I figured the odds of the first zone having the memory we needed were high enough that we should just look there, first, then get fancy only if we need to keep looking. - Some odd hackery was needed to add items to struct zonelist, while not tripping up the custom zonelists built by the mm/mempolicy.c code for MPOL_BIND. My usual wordy comments below explain this. Search for "MPOL_BIND". - Some per-node data in the struct zonelist is now modified frequently, with no locking. Multiple CPU cores on a node could hit and mangle this data. The theory is that this is just performance hint data, and the memory allocator will work just fine despite any such mangling. The fields at risk are the struct 'zonelist_cache' fields 'fullzones' (a bitmask) and 'last_full_zap' (unsigned long jiffies). It should all be self correcting after at most a one second delay. - This still does a linear scan of the same lengths as before. All I've optimized is making the scan faster, not algorithmically shorter. It is now able to scan a compact array of 'unsigned short' in the case of many full nodes, so one cache line should cover quite a few nodes, rather than each node hitting another one or two new and distinct cache lines. - If both Andi and Nick don't find this too complicated, I will be (pleasantly) flabbergasted. - I removed the comment claiming we only use one cachline's worth of zonelist. We seem, at least in the fake numa case, to have put the lie to that claim. - I pay no attention to the various watermarks and such in this performance hint. A node could be marked full for one watermark, and then skipped over when searching for a page using a different watermark. I think that's actually quite ok, as it will tend to slightly increase the spreading of memory over other nodes, away from a memory stressed node. =============== Performance - some benchmark results and analysis: This benchmark runs a memory hog program that uses multiple threads to touch alot of memory as quickly as it can. Multiple runs were made, touching 12, 38, 64 or 90 GBytes out of the total 96 GBytes on the system, and using 1, 19, 37, or 55 threads (on a 56 CPU system.) System, user and real (elapsed) timings were recorded for each run, shown in units of seconds, in the table below. Two kernels were tested - 2.6.18-mm3 and the same kernel with this zonelist caching patch added. The table also shows the percentage improvement the zonelist caching sys time is over (lower than) the stock *-mm kernel. number 2.6.18-mm3 zonelist-cache delta (< 0 good) percent GBs N ------------ -------------- ---------------- systime mem threads sys user real sys user real sys user real better 12 1 153 24 177 151 24 176 -2 0 -1 1% 12 19 99 22 8 99 22 8 0 0 0 0% 12 37 111 25 6 112 25 6 1 0 0 -0% 12 55 115 25 5 110 23 5 -5 -2 0 4% 38 1 502 74 576 497 73 570 -5 -1 -6 0% 38 19 426 78 48 373 76 39 -53 -2 -9 12% 38 37 544 83 36 547 82 36 3 -1 0 -0% 38 55 501 77 23 511 80 24 10 3 1 -1% 64 1 917 125 1042 890 124 1014 -27 -1 -28 2% 64 19 1118 138 119 965 141 103 -153 3 -16 13% 64 37 1202 151 94 1136 150 81 -66 -1 -13 5% 64 55 1118 141 61 1072 140 58 -46 -1 -3 4% 90 1 1342 177 1519 1275 174 1450 -67 -3 -69 4% 90 19 2392 199 192 2116 189 176 -276 -10 -16 11% 90 37 3313 238 175 2972 225 145 -341 -13 -30 10% 90 55 1948 210 104 1843 213 100 -105 3 -4 5% Notes: 1) This test ran a memory hog program that started a specified number N of threads, and had each thread allocate and touch 1/N'th of the total memory to be used in the test run in a single loop, writing a constant word to memory, one store every 4096 bytes. Watching this test during some earlier trial runs, I would see each of these threads sit down on one CPU and stay there, for the remainder of the pass, a different CPU for each thread. 2) The 'real' column is not comparable to the 'sys' or 'user' columns. The 'real' column is seconds wall clock time elapsed, from beginning to end of that test pass. The 'sys' and 'user' columns are total CPU seconds spent on that test pass. For a 19 thread test run, for example, the sum of 'sys' and 'user' could be up to 19 times the number of 'real' elapsed wall clock seconds. 3) Tests were run on a fresh, single-user boot, to minimize the amount of memory already in use at the start of the test, and to minimize the amount of background activity that might interfere. 4) Tests were done on a 56 CPU, 28 Node system with 96 GBytes of RAM. 5) Notice that the 'real' time gets large for the single thread runs, even though the measured 'sys' and 'user' times are modest. I'm not sure what that means - probably something to do with it being slow for one thread to be accessing memory along ways away. Perhaps the fake numa system, running ostensibly the same workload, would not show this substantial degradation of 'real' time for one thread on many nodes -- lets hope not. 6) The high thread count passes (one thread per CPU - on 55 of 56 CPUs) ran quite efficiently, as one might expect. Each pair of threads needed to allocate and touch the memory on the node the two threads shared, a pleasantly parallizable workload. 7) The intermediate thread count passes, when asking for alot of memory forcing them to go to a few neighboring nodes, improved the most with this zonelist caching patch. Conclusions: * This zonelist cache patch probably makes little difference one way or the other for most workloads on real numa hardware, if those workloads avoid heavy off node allocations. * For memory intensive workloads requiring substantial off-node allocations on real numa hardware, this patch improves both kernel and elapsed timings up to ten per-cent. * For fake numa systems, I'm optimistic, but will have to leave that up to Rohit Seth to actually test (once I get him a 2.6.18 backport.) Signed-off-by: Paul Jackson <pj@sgi.com> Cc: Rohit Seth <rohitseth@google.com> Cc: Christoph Lameter <clameter@engr.sgi.com> Cc: David Rientjes <rientjes@cs.washington.edu> Cc: Paul Menage <menage@google.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] Fix do_mbind warning with CONFIG_MIGRATION=nKeith Owens2006-10-11
| | | | | | | | | | | | With CONFIG_MIGRATION=n mm/mempolicy.c: In function 'do_mbind': mm/mempolicy.c:796: warning: passing argument 2 of 'migrate_pages' from incompatible pointer type Signed-off-by: Keith Owens <kaos@ocs.com.au> Cc: Christoph Lameter <clameter@engr.sgi.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] kmemdup: some usersAlexey Dobriyan2006-10-01
| | | | | Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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