From: Michal Hocko <mhocko@kernel.org>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Johannes Weiner <hannes@cmpxchg.org>,
Hugh Dickins <hughd@google.com>,
Daniel Vetter <daniel.vetter@intel.com>,
David Airlie <airlied@linux.ie>,
Mika Westerber <mika.westerberg@intel.com>,
Andrey Ryabinin <ryabinin.a.a@gmail.com>,
linux-mm@kvack.org, LKML <linux-kernel@vger.kernel.org>
Subject: Re: !PageLocked from shmem charge path hits VM_BUG_ON with 4.4-rc4
Date: Mon, 14 Dec 2015 13:06:22 +0100 [thread overview]
Message-ID: <20151214120621.GA4339@dhcp22.suse.cz> (raw)
In-Reply-To: <20151214110320.GB9544@dhcp22.suse.cz>
On Mon 14-12-15 12:03:20, Michal Hocko wrote:
> JFYI: Andrey Ryabinin has noticed that this might be related to
> http://lkml.kernel.org/r/CAPAsAGzrOQAABhOta_o-MzocnikjPtwJLfEKQJ3n5mbBm0T7Bw@mail.gmail.com
>
> and indeed if somebody with pending signals would do wait_on_page_locked
> then it could race AFAIU.
No, a simple lock_page would fail to lock the page (thanks Andrey for
the clarification in the parallel email thread). I have missed that
__lock_page uses bit_wait_io and that would return EINTR when using
signal_pending. The fix has changed that to singnal_pending_state so
this will not happen anymore. I think the mystery is solved...
--
Michal Hocko
SUSE Labs
prev parent reply other threads:[~2015-12-14 12:06 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-12-14 10:01 Michal Hocko
2015-12-14 11:03 ` Michal Hocko
2015-12-14 12:06 ` Michal Hocko [this message]
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