z3fold: fix retry mechanism in page reclaim
authorVitaly Wool <vitalywool@gmail.com>
Mon, 23 Sep 2019 22:33:02 +0000 (15:33 -0700)
committerLinus Torvalds <torvalds@linux-foundation.org>
Tue, 24 Sep 2019 22:54:06 +0000 (15:54 -0700)
commit3f9d2b5766aea06042630ac60b7316fd0cebf06f
tree297838e1dff9482bd655535ee918331a558c3038
parent710ec38b0f633ab3e2581f07a73442d809e28ab0
z3fold: fix retry mechanism in page reclaim

z3fold_page_reclaim()'s retry mechanism is broken: on a second iteration
it will have zhdr from the first one so that zhdr is no longer in line
with struct page.  That leads to crashes when the system is stressed.

Fix that by moving zhdr assignment up.

While at it, protect against using already freed handles by using own
local slots structure in z3fold_page_reclaim().

Link: http://lkml.kernel.org/r/20190908162919.830388dc7404d1e2c80f4095@gmail.com
Signed-off-by: Vitaly Wool <vitalywool@gmail.com>
Reported-by: Markus Linnala <markus.linnala@gmail.com>
Reported-by: Chris Murphy <bugzilla@colorremedies.com>
Reported-by: Agustin Dall'Alba <agustin@dallalba.com.ar>
Cc: "Maciej S. Szmigiero" <mail@maciej.szmigiero.name>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Henry Burns <henrywolfeburns@gmail.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
mm/z3fold.c