* + mm-hugetlb-switch-to-css_tryget-in-hugetlb_cgroup_charge_cgroup.patch added to -mm tree
@ 2019-11-07 1:34 akpm
0 siblings, 0 replies; only message in thread
From: akpm @ 2019-11-07 1:34 UTC (permalink / raw)
To: guro, hannes, mhocko, mm-commits, stable, tj
The patch titled
Subject: mm: hugetlb: switch to css_tryget() in hugetlb_cgroup_charge_cgroup()
has been added to the -mm tree. Its filename is
mm-hugetlb-switch-to-css_tryget-in-hugetlb_cgroup_charge_cgroup.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-hugetlb-switch-to-css_tryget-in-hugetlb_cgroup_charge_cgroup.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-hugetlb-switch-to-css_tryget-in-hugetlb_cgroup_charge_cgroup.patch
Before you just go and hit "reply", please:
a) Consider who else should be cc'ed
b) Prefer to cc a suitable mailing list as well
c) Ideally: find the original patch on the mailing list and do a
reply-to-all to that, adding suitable additional cc's
*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
The -mm tree is included into linux-next and is updated
there every 3-4 working days
------------------------------------------------------
From: Roman Gushchin <guro@fb.com>
Subject: mm: hugetlb: switch to css_tryget() in hugetlb_cgroup_charge_cgroup()
An exiting task might belong to an offline cgroup. In this case an
attempt to grab a cgroup reference from the task can end up with an
infinite loop in hugetlb_cgroup_charge_cgroup(), because neither the
cgroup will become online, neither the task will be migrated to a live
cgroup.
Fix this by switching over to css_tryget(). As css_tryget_online() can't
guarantee that the cgroup won't go offline, in most cases the check
doesn't make sense. In this particular case users of
hugetlb_cgroup_charge_cgroup() are not affected by this change.
A similar problem is described by commit 18fa84a2db0e ("cgroup: Use
css_tryget() instead of css_tryget_online() in task_get_css()").
Link: http://lkml.kernel.org/r/20191106225131.3543616-2-guro@fb.com
Signed-off-by: Roman Gushchin <guro@fb.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Tejun Heo <tj@kernel.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---
mm/hugetlb_cgroup.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/mm/hugetlb_cgroup.c~mm-hugetlb-switch-to-css_tryget-in-hugetlb_cgroup_charge_cgroup
+++ a/mm/hugetlb_cgroup.c
@@ -196,7 +196,7 @@ int hugetlb_cgroup_charge_cgroup(int idx
again:
rcu_read_lock();
h_cg = hugetlb_cgroup_from_task(current);
- if (!css_tryget_online(&h_cg->css)) {
+ if (!css_tryget(&h_cg->css)) {
rcu_read_unlock();
goto again;
}
_
Patches currently in -mm which might be from guro@fb.com are
mm-slab-make-page_cgroup_ino-to-recognize-non-compound-slab-pages-properly.patch
mm-memcg-switch-to-css_tryget-in-get_mem_cgroup_from_mm.patch
mm-hugetlb-switch-to-css_tryget-in-hugetlb_cgroup_charge_cgroup.patch
^ permalink raw reply [flat|nested] only message in thread
only message in thread, other threads:[~2019-11-07 1:34 UTC | newest]
Thread overview: (only message) (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2019-11-07 1:34 + mm-hugetlb-switch-to-css_tryget-in-hugetlb_cgroup_charge_cgroup.patch added to -mm tree akpm
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).