From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wm0-f41.google.com (mail-wm0-f41.google.com [74.125.82.41]) by kanga.kvack.org (Postfix) with ESMTP id 556156B0255 for ; Mon, 14 Dec 2015 07:06:30 -0500 (EST) Received: by wmnn186 with SMTP id n186so117709155wmn.0 for ; Mon, 14 Dec 2015 04:06:30 -0800 (PST) Received: from mail-wm0-f53.google.com (mail-wm0-f53.google.com. [74.125.82.53]) by mx.google.com with ESMTPS id t200si8345175wmt.109.2015.12.14.04.06.24 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 14 Dec 2015 04:06:24 -0800 (PST) Received: by wmpp66 with SMTP id p66so57795514wmp.1 for ; Mon, 14 Dec 2015 04:06:24 -0800 (PST) Date: Mon, 14 Dec 2015 13:06:22 +0100 From: Michal Hocko Subject: Re: !PageLocked from shmem charge path hits VM_BUG_ON with 4.4-rc4 Message-ID: <20151214120621.GA4339@dhcp22.suse.cz> References: <20151214100156.GA4540@dhcp22.suse.cz> <20151214110320.GB9544@dhcp22.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20151214110320.GB9544@dhcp22.suse.cz> Sender: owner-linux-mm@kvack.org List-ID: To: Linus Torvalds Cc: Andrew Morton , Johannes Weiner , Hugh Dickins , Daniel Vetter , David Airlie , Mika Westerber , Andrey Ryabinin , linux-mm@kvack.org, LKML 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 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org