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authorLi Zefan <lizf@cn.fujitsu.com>2008-11-06 12:53:32 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2008-11-06 15:41:19 -0800
commit24eb089950ce44603b30a3145a2c8520e2b55bb1 (patch)
tree3cccd3e15589c693c8c4e6484a938d2343ef1abc /Documentation
parentb41ad14c30acf023d09ac064096a4cf41248ce46 (diff)
cgroups: fix invalid cgrp->dentry before cgroup has been completely removed
This fixes an oops when reading /proc/sched_debug. A cgroup won't be removed completely until finishing cgroup_diput(), so we shouldn't invalidate cgrp->dentry in cgroup_rmdir(). Otherwise, when a group is being removed while cgroup_path() gets called, we may trigger NULL dereference BUG. The bug can be reproduced: # cat test.sh #!/bin/sh mount -t cgroup -o cpu xxx /mnt for (( ; ; )) { mkdir /mnt/sub rmdir /mnt/sub } # ./test.sh & # cat /proc/sched_debug BUG: unable to handle kernel NULL pointer dereference at 00000038 IP: [<c045a47f>] cgroup_path+0x39/0x90 ... Call Trace: [<c0420344>] ? print_cfs_rq+0x6e/0x75d [<c0421160>] ? sched_debug_show+0x72d/0xc1e ... Signed-off-by: Li Zefan <lizf@cn.fujitsu.com> Acked-by: Paul Menage <menage@google.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Ingo Molnar <mingo@elte.hu> Cc: <stable@kernel.org> [2.6.26.x, 2.6.27.x] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'Documentation')
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