diff options
author | Shailabh Nagar <nagar@watson.ibm.com> | 2006-07-14 03:24:47 -0400 |
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committer | Linus Torvalds <torvalds@g5.osdl.org> | 2006-07-15 00:53:57 -0400 |
commit | bb129994c3bff9c5e8df91f05d7e9b6402fbd83f (patch) | |
tree | 8d8c4e27af727c9de42ac6aeae04f70537e6bd01 /include/asm-parisc | |
parent | f9fd8914c1acca0d98b69d831b128d5b52f03c51 (diff) |
[PATCH] Remove down_write() from taskstats code invoked on the exit() path
In send_cpu_listeners(), which is called on the exit path, a down_write()
was protecting operations like skb_clone() and genlmsg_unicast() that do
GFP_KERNEL allocations. If the oom-killer decides to kill tasks to satisfy
the allocations,the exit of those tasks could block on the same semphore.
The down_write() was only needed to allow removal of invalid listeners from
the listener list. The patch converts the down_write to a down_read and
defers the removal to a separate critical region. This ensures that even
if the oom-killer is called, no other task's exit is blocked as it can
still acquire another down_read.
Thanks to Andrew Morton & Herbert Xu for pointing out the oom related
pitfalls, and to Chandra Seetharaman for suggesting this fix instead of
using something more complex like RCU.
Signed-off-by: Chandra Seetharaman <sekharan@us.ibm.com>
Signed-off-by: Shailabh Nagar <nagar@watson.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'include/asm-parisc')
0 files changed, 0 insertions, 0 deletions