Subject: + oom_kill-add-rcu_read_lock-into-find_lock_task_mm.patch added to -mm tree
To: oleg@xxxxxxxxxx,dserrg@xxxxxxxxx,ebiederm@xxxxxxxxxxxx,fweisbec@xxxxxxxxx,mhocko@xxxxxxx,msb@xxxxxxxxxxxx,rientjes@xxxxxxxxxx,snanda@xxxxxxxxxxxx,xiaobing.tu@xxxxxxxxx,xindong.ma@xxxxxxxxx
From: akpm@xxxxxxxxxxxxxxxxxxxx
Date: Mon, 09 Dec 2013 15:07:37 -0800
The patch titled
Subject: oom_kill: add rcu_read_lock() into find_lock_task_mm()
has been added to the -mm tree. Its filename is
oom_kill-add-rcu_read_lock-into-find_lock_task_mm.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/oom_kill-add-rcu_read_lock-into-find_lock_task_mm.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/oom_kill-add-rcu_read_lock-into-find_lock_task_mm.patch
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------------------------------------------------------
From: Oleg Nesterov <oleg@xxxxxxxxxx>
Subject: oom_kill: add rcu_read_lock() into find_lock_task_mm()
find_lock_task_mm() expects it is called under rcu or tasklist lock, but
it seems that at least oom_unkillable_task()->task_in_mem_cgroup() and
mem_cgroup_out_of_memory()->oom_badness() can call it lockless.
Perhaps we could fix the callers, but this patch simply adds rcu lock into
find_lock_task_mm(). This also allows to simplify a bit one of its
callers, oom_kill_process().
Signed-off-by: Oleg Nesterov <oleg@xxxxxxxxxx>
Cc: Sergey Dyasly <dserrg@xxxxxxxxx>
Cc: Sameer Nanda <snanda@xxxxxxxxxxxx>
Cc: "Eric W. Biederman" <ebiederm@xxxxxxxxxxxx>
Cc: Frederic Weisbecker <fweisbec@xxxxxxxxx>
Cc: Mandeep Singh Baines <msb@xxxxxxxxxxxx>
Cc: "Ma, Xindong" <xindong.ma@xxxxxxxxx>
Reviewed-by: Michal Hocko <mhocko@xxxxxxx>
Cc: "Tu, Xiaobing" <xiaobing.tu@xxxxxxxxx>
Acked-by: David Rientjes <rientjes@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/oom_kill.c | 12 ++++++++----
1 file changed, 8 insertions(+), 4 deletions(-)
diff -puN mm/oom_kill.c~oom_kill-add-rcu_read_lock-into-find_lock_task_mm mm/oom_kill.c
--- a/mm/oom_kill.c~oom_kill-add-rcu_read_lock-into-find_lock_task_mm
+++ a/mm/oom_kill.c
@@ -102,14 +102,19 @@ struct task_struct *find_lock_task_mm(st
{
struct task_struct *t;
+ rcu_read_lock();
+
for_each_thread(p, t) {
task_lock(t);
if (likely(t->mm))
- return t;
+ goto found;
task_unlock(t);
}
+ t = NULL;
+found:
+ rcu_read_unlock();
- return NULL;
+ return t;
}
/* return true if the task is not adequate as candidate victim task. */
@@ -461,10 +466,8 @@ void oom_kill_process(struct task_struct
}
read_unlock(&tasklist_lock);
- rcu_read_lock();
p = find_lock_task_mm(victim);
if (!p) {
- rcu_read_unlock();
put_task_struct(victim);
return;
} else if (victim != p) {
@@ -490,6 +493,7 @@ void oom_kill_process(struct task_struct
* That thread will now get access to memory reserves since it has a
* pending fatal signal.
*/
+ rcu_read_lock();
for_each_process(p)
if (p->mm == mm && !same_thread_group(p, victim) &&
!(p->flags & PF_KTHREAD)) {
_
Patches currently in -mm which might be from oleg@xxxxxxxxxx are
introduce-for_each_thread-to-replace-the-buggy-while_each_thread.patch
oom_kill-change-oom_killc-to-use-for_each_thread.patch
oom_kill-has_intersects_mems_allowed-needs-rcu_read_lock.patch
oom_kill-add-rcu_read_lock-into-find_lock_task_mm.patch
autofs4-allow-autofs-to-work-outside-the-initial-pid-namespace.patch
autofs4-translate-pids-to-the-right-namespace-for-the-daemon.patch
coredump-set_dumpable-fix-the-theoretical-race-with-itself.patch
coredump-kill-mmf_dumpable-and-mmf_dump_securely.patch
coredump-make-__get_dumpable-get_dumpable-inline-kill-fs-coredumph.patch
proc-cleanup-simplify-get_task_state-task_state_array.patch
proc-fix-the-potential-use-after-free-in-first_tid.patch
proc-change-first_tid-to-use-while_each_thread-rather-than-next_thread.patch
proc-dont-abuse-group_leader-in-proc_task_readdir-paths.patch
proc-fix-f_pos-overflows-in-first_tid.patch
kernel-forkc-remove-redundant-null-check-in-dup_mm.patch
exec-check_unsafe_exec-use-while_each_thread-rather-than-next_thread.patch
exec-check_unsafe_exec-kill-the-dead-eagain-and-clear_in_exec-logic.patch
exec-move-the-final-allow_write_access-fput-into-free_bprm.patch
exec-kill-task_struct-did_exec.patch
fs-proc-arrayc-change-do_task_stat-to-use-while_each_thread.patch
kernel-sysc-k_getrusage-can-use-while_each_thread.patch
kernel-signalc-change-do_signal_stop-do_sigaction-to-use-while_each_thread.patch
linux-next.patch
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