/proc/*/oom_score oops re badness
commit19c5d45a09312ca20cd1f9df3fd1a87fe0cb8aac
authorAlexey Dobriyan <adobriyan@sw.ru>
Tue, 8 May 2007 07:26:46 +0000 (8 00:26 -0700)
committerLinus Torvalds <torvalds@woody.linux-foundation.org>
Tue, 8 May 2007 18:15:04 +0000 (8 11:15 -0700)
treede228e847ea4846e77cd64b35ca74eb5daa3d242
parent72c1bbf308c75a136803d2d76d0e18258be14c7a
/proc/*/oom_score oops re badness

Eternal quest to make

while true; do cat /proc/fs/xfs/stat >/dev/null 2>/dev/null; done
while true; do find /proc -type f 2>/dev/null | xargs cat >/dev/null 2>/dev/null; done
while true; do modprobe xfs; rmmod xfs; done

work reliably continues and now kernel oopses in the following way:

BUG: unable to handle ... at virtual address 6b6b6b6b
EIP is at badness
process: cat
proc_oom_score
proc_info_read
sys_fstat64
vfs_read
proc_info_read
sys_read

Failing code is prefetch hidden in list_for_each_entry() in badness().
badness() is reachable from two points. One is proc_oom_score, another
is out_of_memory() => select_bad_process() => badness().

Second path grabs tasklist_lock, while first doesn't.

Signed-off-by: Alexey Dobriyan <adobriyan@sw.ru>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
fs/proc/base.c