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authorMichal Hocko <mhocko@suse.com>2019-02-21 09:19:42 +0300
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2019-02-27 12:08:01 +0300
commite69eb7e8a0c70f2316228aefa3cbf87a190d8fd0 (patch)
tree0715aff3a7999dc057b49e10f091f3d6a85eb68e /fs/proc
parent3af9907c2a544d3d3a55f68cb75018a98b4c1899 (diff)
downloadlinux-e69eb7e8a0c70f2316228aefa3cbf87a190d8fd0.tar.xz
proc, oom: do not report alien mms when setting oom_score_adj
commit b2b469939e93458753cfbf8282ad52636495965e upstream. Tetsuo has reported that creating a thousands of processes sharing MM without SIGHAND (aka alien threads) and setting /proc/<pid>/oom_score_adj will swamp the kernel log and takes ages [1] to finish. This is especially worrisome that all that printing is done under RCU lock and this can potentially trigger RCU stall or softlockup detector. The primary reason for the printk was to catch potential users who might depend on the behavior prior to 44a70adec910 ("mm, oom_adj: make sure processes sharing mm have same view of oom_score_adj") but after more than 2 years without a single report I guess it is safe to simply remove the printk altogether. The next step should be moving oom_score_adj over to the mm struct and remove all the tasks crawling as suggested by [2] [1] http://lkml.kernel.org/r/97fce864-6f75-bca5-14bc-12c9f890e740@i-love.sakura.ne.jp [2] http://lkml.kernel.org/r/20190117155159.GA4087@dhcp22.suse.cz Link: http://lkml.kernel.org/r/20190212102129.26288-1-mhocko@kernel.org Signed-off-by: Michal Hocko <mhocko@suse.com> Reported-by: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: David Rientjes <rientjes@google.com> Cc: Yong-Taek Lee <ytk.lee@samsung.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'fs/proc')
-rw-r--r--fs/proc/base.c4
1 files changed, 0 insertions, 4 deletions
diff --git a/fs/proc/base.c b/fs/proc/base.c
index 9063738ff1f0..64695dcf89f3 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -1108,10 +1108,6 @@ static int __set_oom_adj(struct file *file, int oom_adj, bool legacy)
task_lock(p);
if (!p->vfork_done && process_shares_mm(p, mm)) {
- pr_info("updating oom_score_adj for %d (%s) from %d to %d because it shares mm with %d (%s). Report if this is unexpected.\n",
- task_pid_nr(p), p->comm,
- p->signal->oom_score_adj, oom_adj,
- task_pid_nr(task), task->comm);
p->signal->oom_score_adj = oom_adj;
if (!legacy && has_capability_noaudit(current, CAP_SYS_RESOURCE))
p->signal->oom_score_adj_min = (short)oom_adj;