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Commit 51006672 authored by Vitaly Wool's avatar Vitaly Wool Committed by Greg Kroah-Hartman
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z3fold: fix possible reclaim races

[ Upstream commit ca0246bb97c23da9d267c2107c07fb77e38205c9 ]

Reclaim and free can race on an object which is basically fine but in
order for reclaim to be able to map "freed" object we need to encode
object length in the handle.  handle_to_chunks() is then introduced to
extract object length from a handle and use it during mapping.

Moreover, to avoid racing on a z3fold "headless" page release, we should
not try to free that page in z3fold_free() if the reclaim bit is set.
Also, in the unlikely case of trying to reclaim a page being freed, we
should not proceed with that page.

While at it, fix the page accounting in reclaim function.

This patch supersedes "[PATCH] z3fold: fix reclaim lock-ups".

Link: http://lkml.kernel.org/r/20181105162225.74e8837d03583a9b707cf559@gmail.com


Signed-off-by: default avatarVitaly Wool <vitaly.vul@sony.com>
Signed-off-by: default avatarJongseok Kim <ks77sj@gmail.com>
Reported-by-by: default avatarJongseok Kim <ks77sj@gmail.com>
Reviewed-by: default avatarSnild Dolkow <snild@sony.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: default avatarSasha Levin <sashal@kernel.org>
parent 43b2ceb0
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