Commit 6c4687cc authored by Oleg Nesterov's avatar Oleg Nesterov Committed by Ingo Molnar

uprobes: Fix the memcg accounting

__replace_page() wronlgy calls mem_cgroup_cancel_charge() in "success" path,
it should only do this if page_check_address() fails.

This means that every enable/disable leads to unbalanced mem_cgroup_uncharge()
from put_page(old_page), it is trivial to underflow the page_counter->count
and trigger OOM.
Reported-and-tested-by: default avatarBrenden Blanco <bblanco@plumgrid.com>
Signed-off-by: default avatarOleg Nesterov <oleg@redhat.com>
Reviewed-by: default avatarJohannes Weiner <hannes@cmpxchg.org>
Acked-by: default avatarMichal Hocko <mhocko@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vladimir Davydov <vdavydov@virtuozzo.com>
Cc: stable@vger.kernel.org # 3.17+
Fixes: 00501b53 ("mm: memcontrol: rewrite charge API")
Link: http://lkml.kernel.org/r/20160817153629.GB29724@redhat.comSigned-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent 3cace81e
...@@ -172,8 +172,10 @@ static int __replace_page(struct vm_area_struct *vma, unsigned long addr, ...@@ -172,8 +172,10 @@ static int __replace_page(struct vm_area_struct *vma, unsigned long addr,
mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end); mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end);
err = -EAGAIN; err = -EAGAIN;
ptep = page_check_address(page, mm, addr, &ptl, 0); ptep = page_check_address(page, mm, addr, &ptl, 0);
if (!ptep) if (!ptep) {
mem_cgroup_cancel_charge(kpage, memcg, false);
goto unlock; goto unlock;
}
get_page(kpage); get_page(kpage);
page_add_new_anon_rmap(kpage, vma, addr, false); page_add_new_anon_rmap(kpage, vma, addr, false);
...@@ -200,7 +202,6 @@ static int __replace_page(struct vm_area_struct *vma, unsigned long addr, ...@@ -200,7 +202,6 @@ static int __replace_page(struct vm_area_struct *vma, unsigned long addr,
err = 0; err = 0;
unlock: unlock:
mem_cgroup_cancel_charge(kpage, memcg, false);
mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end); mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
unlock_page(page); unlock_page(page);
return err; return err;
......
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