5 files changed, 42 insertions, 9 deletions

diff --git a/mm/Kconfig b/mm/Kconfig
index b53427ad30a3..57971d2ab848 100644
--- a/mm/Kconfig
+++ b/mm/Kconfig
@@ -213,6 +213,8 @@ config UNEVICTABLE_LRU
           will use one page flag and increase the code size a little,
           say Y unless you know what you are doing.
 
+          See Documentation/vm/unevictable-lru.txt for more information.
+
 config HAVE_MLOCK
         bool
         default y if MMU=y
diff --git a/mm/filemap.c b/mm/filemap.c
index 2e2d38ebda4b..8bd498040f32 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -567,8 +567,8 @@ EXPORT_SYMBOL(wait_on_page_bit);
 
 /**
  * add_page_wait_queue - Add an arbitrary waiter to a page's wait queue
- * @page - Page defining the wait queue of interest
- * @waiter - Waiter to add to the queue
+ * @page: Page defining the wait queue of interest
+ * @waiter: Waiter to add to the queue
  *
  * Add an arbitrary @waiter to the wait queue for the nominated @page.
  */
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 2fc6d6c48238..e44fb0fbb80e 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -932,7 +932,7 @@ static int __mem_cgroup_try_charge(struct mm_struct *mm,
         if (unlikely(!mem))
                 return 0;
 
-        VM_BUG_ON(mem_cgroup_is_obsolete(mem));
+        VM_BUG_ON(!mem || mem_cgroup_is_obsolete(mem));
 
         while (1) {
                 int ret;
diff --git a/mm/shmem.c b/mm/shmem.c
index d94d2e9146bc..f9cb20ebb990 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -24,6 +24,7 @@
 #include <linux/init.h>
 #include <linux/vfs.h>
 #include <linux/mount.h>
+#include <linux/pagemap.h>
 #include <linux/file.h>
 #include <linux/mm.h>
 #include <linux/module.h>
@@ -43,7 +44,6 @@ static struct vfsmount *shm_mnt;
 #include <linux/exportfs.h>
 #include <linux/generic_acl.h>
 #include <linux/mman.h>
-#include <linux/pagemap.h>
 #include <linux/string.h>
 #include <linux/slab.h>
 #include <linux/backing-dev.h>
@@ -65,13 +65,28 @@ static struct vfsmount *shm_mnt;
 #include <asm/div64.h>
 #include <asm/pgtable.h>
 
+/*
+ * The maximum size of a shmem/tmpfs file is limited by the maximum size of
+ * its triple-indirect swap vector - see illustration at shmem_swp_entry().
+ *
+ * With 4kB page size, maximum file size is just over 2TB on a 32-bit kernel,
+ * but one eighth of that on a 64-bit kernel.  With 8kB page size, maximum
+ * file size is just over 4TB on a 64-bit kernel, but 16TB on a 32-bit kernel,
+ * MAX_LFS_FILESIZE being then more restrictive than swap vector layout.
+ *
+ * We use / and * instead of shifts in the definitions below, so that the swap
+ * vector can be tested with small even values (e.g. 20) for ENTRIES_PER_PAGE.
+ */
 #define ENTRIES_PER_PAGE (PAGE_CACHE_SIZE/sizeof(unsigned long))
-#define ENTRIES_PER_PAGEPAGE (ENTRIES_PER_PAGE*ENTRIES_PER_PAGE)
-#define BLOCKS_PER_PAGE  (PAGE_CACHE_SIZE/512)
+#define ENTRIES_PER_PAGEPAGE ((unsigned long long)ENTRIES_PER_PAGE*ENTRIES_PER_PAGE)
 
-#define SHMEM_MAX_INDEX  (SHMEM_NR_DIRECT + (ENTRIES_PER_PAGEPAGE/2) * (ENTRIES_PER_PAGE+1))
-#define SHMEM_MAX_BYTES  ((unsigned long long)SHMEM_MAX_INDEX << PAGE_CACHE_SHIFT)
+#define SHMSWP_MAX_INDEX (SHMEM_NR_DIRECT + (ENTRIES_PER_PAGEPAGE/2) * (ENTRIES_PER_PAGE+1))
+#define SHMSWP_MAX_BYTES (SHMSWP_MAX_INDEX << PAGE_CACHE_SHIFT)
 
+#define SHMEM_MAX_BYTES  min_t(unsigned long long, SHMSWP_MAX_BYTES, MAX_LFS_FILESIZE)
+#define SHMEM_MAX_INDEX  ((unsigned long)((SHMEM_MAX_BYTES+1) >> PAGE_CACHE_SHIFT))
+
+#define BLOCKS_PER_PAGE  (PAGE_CACHE_SIZE/512)
 #define VM_ACCT(size)    (PAGE_CACHE_ALIGN(size) >> PAGE_SHIFT)
 
 /* info->flags needs VM_flags to handle pagein/truncate races efficiently */
@@ -2581,7 +2596,7 @@ int shmem_unuse(swp_entry_t entry, struct page *page)
 #define shmem_get_inode(sb, mode, dev, flags)   ramfs_get_inode(sb, mode, dev)
 #define shmem_acct_size(flags, size)            0
 #define shmem_unacct_size(flags, size)          do {} while (0)
-#define SHMEM_MAX_BYTES                         LLONG_MAX
+#define SHMEM_MAX_BYTES                         MAX_LFS_FILESIZE
 
 #endif /* CONFIG_SHMEM */
 
diff --git a/mm/util.c b/mm/util.c
index 2599e83eea17..55bef160b9f1 100644
--- a/mm/util.c
+++ b/mm/util.c
@@ -223,6 +223,22 @@ void arch_pick_mmap_layout(struct mm_struct *mm)
 }
 #endif
 
+/**
+ * get_user_pages_fast() - pin user pages in memory
+ * @start:      starting user address
+ * @nr_pages:   number of pages from start to pin
+ * @write:      whether pages will be written to
+ * @pages:      array that receives pointers to the pages pinned.
+ *              Should be at least nr_pages long.
+ *
+ * Attempt to pin user pages in memory without taking mm->mmap_sem.
+ * If not successful, it will fall back to taking the lock and
+ * calling get_user_pages().
+ *
+ * Returns number of pages pinned. This may be fewer than the number
+ * requested. If nr_pages is 0 or negative, returns 0. If no pages
+ * were pinned, returns -errno.
+ */
 int __attribute__((weak)) get_user_pages_fast(unsigned long start,
                                 int nr_pages, int write, struct page **pages)
 {