From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 3DF5CC18E5B for ; Wed, 11 Mar 2020 00:48:53 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id EFF5C21D56 for ; Wed, 11 Mar 2020 00:48:52 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org EFF5C21D56 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=intel.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id B6E936B0003; Tue, 10 Mar 2020 20:48:51 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id B1F5D6B0006; Tue, 10 Mar 2020 20:48:51 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id A0D836B0007; Tue, 10 Mar 2020 20:48:51 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0249.hostedemail.com [216.40.44.249]) by kanga.kvack.org (Postfix) with ESMTP id 86AAF6B0003 for ; Tue, 10 Mar 2020 20:48:51 -0400 (EDT) Received: from smtpin11.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay04.hostedemail.com (Postfix) with ESMTP id 534B51EF3 for ; Wed, 11 Mar 2020 00:48:51 +0000 (UTC) X-FDA: 76581246462.11.stick08_6a573e864b009 X-HE-Tag: stick08_6a573e864b009 X-Filterd-Recvd-Size: 3643 Received: from mga14.intel.com (mga14.intel.com [192.55.52.115]) by imf29.hostedemail.com (Postfix) with ESMTP for ; Wed, 11 Mar 2020 00:48:50 +0000 (UTC) X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga002.fm.intel.com ([10.253.24.26]) by fmsmga103.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 10 Mar 2020 17:48:49 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.70,538,1574150400"; d="scan'208";a="277172633" Received: from yhuang-dev.sh.intel.com (HELO yhuang-dev) ([10.239.159.23]) by fmsmga002.fm.intel.com with ESMTP; 10 Mar 2020 17:48:47 -0700 From: "Huang\, Ying" To: Qian Cai Cc: , , , , Subject: Re: [PATCH] page-flags: fix a crash at SetPageError(THP_SWAP) References: <20200310235846.1319-1-cai@lca.pw> Date: Wed, 11 Mar 2020 08:48:47 +0800 In-Reply-To: <20200310235846.1319-1-cai@lca.pw> (Qian Cai's message of "Tue, 10 Mar 2020 19:58:46 -0400") Message-ID: <87pndjwwb4.fsf@yhuang-dev.intel.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/26.1 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=ascii X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: Qian Cai writes: > The commit bd4c82c22c36 ("mm, THP, swap: delay splitting THP after > swapped out") supported writing THP to a swap device but forgot to > upgrade an older commit df8c94d13c7e ("page-flags: define behavior of > FS/IO-related flags on compound pages") which could trigger a crash > during THP swapping out with DEBUG_VM_PGFLAGS=y, > > kernel BUG at include/linux/page-flags.h:317! > > page dumped because: VM_BUG_ON_PAGE(1 && PageCompound(page)) > page:fffff3b2ec3a8000 refcount:512 mapcount:0 mapping:000000009eb0338c > index:0x7f6e58200 head:fffff3b2ec3a8000 order:9 compound_mapcount:0 > compound_pincount:0 > anon flags: > 0x45fffe0000d8454(uptodate|lru|workingset|owner_priv_1|writeback|head|reclaim|swapbacked) > > end_swap_bio_write() > SetPageError(page) > VM_BUG_ON_PAGE(1 && PageCompound(page)) > > > bio_endio+0x297/0x560 > dec_pending+0x218/0x430 [dm_mod] > clone_endio+0xe4/0x2c0 [dm_mod] > bio_endio+0x297/0x560 > blk_update_request+0x201/0x920 > scsi_end_request+0x6b/0x4b0 > scsi_io_completion+0x509/0x7e0 > scsi_finish_command+0x1ed/0x2a0 > scsi_softirq_done+0x1c9/0x1d0 > __blk_mqnterrupt+0xf/0x20 > > > Fix by checking PF_NO_TAIL in those places instead. > > Fixes: bd4c82c22c36 ("mm, THP, swap: delay splitting THP after swapped out") > Cc: > Signed-off-by: Qian Cai Good catch! Thanks! Acked-by: "Huang, Ying" > --- > include/linux/page-flags.h | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h > index 1bf83c8fcaa7..77de28bfefb0 100644 > --- a/include/linux/page-flags.h > +++ b/include/linux/page-flags.h > @@ -311,7 +311,7 @@ static inline int TestClearPage##uname(struct page *page) { return 0; } > > __PAGEFLAG(Locked, locked, PF_NO_TAIL) > PAGEFLAG(Waiters, waiters, PF_ONLY_HEAD) __CLEARPAGEFLAG(Waiters, waiters, PF_ONLY_HEAD) > -PAGEFLAG(Error, error, PF_NO_COMPOUND) TESTCLEARFLAG(Error, error, PF_NO_COMPOUND) > +PAGEFLAG(Error, error, PF_NO_TAIL) TESTCLEARFLAG(Error, error, PF_NO_TAIL) > PAGEFLAG(Referenced, referenced, PF_HEAD) > TESTCLEARFLAG(Referenced, referenced, PF_HEAD) > __SETPAGEFLAG(Referenced, referenced, PF_HEAD)