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 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 64F3CC433EF for ; Wed, 6 Oct 2021 17:58:30 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 51B6761151 for ; Wed, 6 Oct 2021 17:58:30 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229565AbhJFSAV (ORCPT ); Wed, 6 Oct 2021 14:00:21 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59160 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S238900AbhJFSAS (ORCPT ); Wed, 6 Oct 2021 14:00:18 -0400 Received: from mail-ed1-x530.google.com (mail-ed1-x530.google.com [IPv6:2a00:1450:4864:20::530]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8B184C061746 for ; Wed, 6 Oct 2021 10:58:25 -0700 (PDT) Received: by mail-ed1-x530.google.com with SMTP id g10so12590769edj.1 for ; Wed, 06 Oct 2021 10:58:25 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=TDI52nHDnY3e5RS/+G6Fr1mYHqPbZc0znit1nNpWvHw=; b=mjJfAEBb3dub9dxOGjoq//4tjQuyNsRiJ0soLFa7uVprcMzHr7WPusR8nPYv4b0G/S Nglfgfy61FfiDkTSpAZw6k8XBrCJAYanReo5vVwpiSU4Gp/Su6ttyRgpoM3ixEWf0KH7 Zh1gilmBmi2Vy7m6NY1q4lqF8mEU+mDQxdvlHV8UGRLeWhfvbApZxwX/4dr8J+6oInea PH606dIE/+8yPL6EFP6LbLFDpASm38OJhcn53wD6reCTyXgfKogWh2o1jPKp5KV0undX zH0H27W7zAeYwXZZA2bv/zxp7RLfbPn0phFtjLeIuJO6ru9sEks6Q9qyy/SETRIIPfPI YXVg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=TDI52nHDnY3e5RS/+G6Fr1mYHqPbZc0znit1nNpWvHw=; b=NSUqhWcDqsEpG/wWeD2JJ8yxliP35TfQ5rOrJn0m9imriMSm3eDswRQA8zwlpyFSCa kHjlPMkvHL952NEG7TTB+StfUlbiVpTl6aP2+z4v6IOCsb2trQrMq9MQyVIiGePhOnPs Uilf7Zdl5Y+wHUf6CWKW5JgFYSwEu0rWZMoVjmKx1S08NwdgsHEDqJ8h+UPBkGqhNQAJ aYRaoXboCjixuSu/NT9Onnldmp4Ax6QuUDHOO6dzSEjsOW2Qf0XZ0Dcc3wD6H9cR1JS0 s4t9D+/X0BuLocUYtT8h51sZjUK5MbUiJmbimApviTjNeLUy7VaaLE6Fg0EXoAurDuOY Y23g== X-Gm-Message-State: AOAM530GIMJubp2mB349NDDUh2QlHdkp+pusHEXOYrDSFEfM8IVMcF0X AiUeYveiEQQp0RSf0JQrXM7UXqefb3IwhS+K63o= X-Google-Smtp-Source: ABdhPJxdaGkvWty6OMaxnZMJJuUXS3QSP5YDT2B22jdwuDCzVSheXSlzRUBJkKakCZs42bRRvC9Wt17qr4pJ/1HU0aY= X-Received: by 2002:a17:906:3f83:: with SMTP id b3mr35036446ejj.233.1633543101931; Wed, 06 Oct 2021 10:58:21 -0700 (PDT) MIME-Version: 1.0 References: <20210906121200.57905-1-rongwei.wang@linux.alibaba.com> <20211006021837.59721-1-rongwei.wang@linux.alibaba.com> <20211006021837.59721-3-rongwei.wang@linux.alibaba.com> In-Reply-To: <20211006021837.59721-3-rongwei.wang@linux.alibaba.com> From: Yang Shi Date: Wed, 6 Oct 2021 10:58:10 -0700 Message-ID: Subject: Re: [PATCH v3 v3 2/2] mm, thp: bail out early in collapse_file for writeback page To: Rongwei Wang Cc: Linux MM , Linux Kernel Mailing List , Andrew Morton , Matthew Wilcox , Song Liu , William Kucharski , Hugh Dickins Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Oct 5, 2021 at 7:18 PM Rongwei Wang wrote: > > Currently collapse_file does not explicitly check PG_writeback, instead, > page_has_private and try_to_release_page are used to filter writeback > pages. This does not work for xfs with blocksize equal to or larger > than pagesize, because in such case xfs has no page->private. > > This makes collapse_file bail out early for writeback page. Otherwise, > xfs end_page_writeback will panic as follows. > > [ 6411.448211] page:fffffe00201bcc80 refcount:0 mapcount:0 mapping:ffff0003f88c86a8 index:0x0 pfn:0x84ef32 > [ 6411.448304] aops:xfs_address_space_operations [xfs] ino:30000b7 dentry name:"libtest.so" > [ 6411.448312] flags: 0x57fffe0000008027(locked|referenced|uptodate|active|writeback) > [ 6411.448317] raw: 57fffe0000008027 ffff80001b48bc28 ffff80001b48bc28 ffff0003f88c86a8 > [ 6411.448321] raw: 0000000000000000 0000000000000000 00000000ffffffff ffff0000c3e9a000 > [ 6411.448324] page dumped because: VM_BUG_ON_PAGE(((unsigned int) page_ref_count(page) + 127u <= 127u)) > [ 6411.448327] page->mem_cgroup:ffff0000c3e9a000 > [ 6411.448340] ------------[ cut here ]------------ > [ 6411.448343] kernel BUG at include/linux/mm.h:1212! > [ 6411.449288] Internal error: Oops - BUG: 0 [#1] SMP > [ 6411.449786] Modules linked in: > [ 6411.449790] BUG: Bad page state in process khugepaged pfn:84ef32 > [ 6411.450143] xfs(E) > [ 6411.450459] page:fffffe00201bcc80 refcount:0 mapcount:0 mapping:0 index:0x0 pfn:0x84ef32 > [ 6411.451361] libcrc32c(E) rfkill(E) aes_ce_blk(E) crypto_simd(E) ... > [ 6411.451387] CPU: 25 PID: 0 Comm: swapper/25 Kdump: loaded Tainted: ... > [ 6411.451389] pstate: 60400005 (nZCv daif +PAN -UAO -TCO BTYPE=--) > [ 6411.451393] pc : end_page_writeback+0x1c0/0x214 > [ 6411.451394] lr : end_page_writeback+0x1c0/0x214 > [ 6411.451395] sp : ffff800011ce3cc0 > [ 6411.451396] x29: ffff800011ce3cc0 x28: 0000000000000000 > [ 6411.451398] x27: ffff000c04608040 x26: 0000000000000000 > [ 6411.451399] x25: ffff000c04608040 x24: 0000000000001000 > [ 6411.451401] x23: ffff0003f88c8530 x22: 0000000000001000 > [ 6411.451403] x21: ffff0003f88c8530 x20: 0000000000000000 > [ 6411.451404] x19: fffffe00201bcc80 x18: 0000000000000030 > [ 6411.451406] x17: 0000000000000000 x16: 0000000000000000 > [ 6411.451407] x15: ffff000c018f9760 x14: ffffffffffffffff > [ 6411.451409] x13: ffff8000119d72b0 x12: ffff8000119d6ee3 > [ 6411.451410] x11: ffff8000117b69b8 x10: 00000000ffff8000 > [ 6411.451412] x9 : ffff800010617534 x8 : 0000000000000000 > [ 6411.451413] x7 : ffff8000114f69b8 x6 : 000000000000000f > [ 6411.451415] x5 : 0000000000000000 x4 : 0000000000000000 > [ 6411.451416] x3 : 0000000000000400 x2 : 0000000000000000 > [ 6411.451418] x1 : 0000000000000000 x0 : 0000000000000000 > [ 6411.451420] Call trace: > [ 6411.451421] end_page_writeback+0x1c0/0x214 > [ 6411.451424] iomap_finish_page_writeback+0x13c/0x204 > [ 6411.451425] iomap_finish_ioend+0xe8/0x19c > [ 6411.451426] iomap_writepage_end_bio+0x38/0x50 > [ 6411.451427] bio_endio+0x168/0x1ec > [ 6411.451430] blk_update_request+0x278/0x3f0 > [ 6411.451432] blk_mq_end_request+0x34/0x15c > [ 6411.451435] virtblk_request_done+0x38/0x74 [virtio_blk] > [ 6411.451437] blk_done_softirq+0xc4/0x110 > [ 6411.451439] __do_softirq+0x128/0x38c > [ 6411.451441] __irq_exit_rcu+0x118/0x150 > [ 6411.451442] irq_exit+0x1c/0x30 > [ 6411.451445] __handle_domain_irq+0x8c/0xf0 > [ 6411.451446] gic_handle_irq+0x84/0x108 > [ 6411.451447] el1_irq+0xcc/0x180 > [ 6411.451448] arch_cpu_idle+0x18/0x40 > [ 6411.451450] default_idle_call+0x4c/0x1a0 > [ 6411.451453] cpuidle_idle_call+0x168/0x1e0 > [ 6411.451454] do_idle+0xb4/0x104 > [ 6411.451455] cpu_startup_entry+0x30/0x9c > [ 6411.451458] secondary_start_kernel+0x104/0x180 > [ 6411.451460] Code: d4210000 b0006161 910c8021 94013f4d (d4210000) > [ 6411.451462] ---[ end trace 4a88c6a074082f8c ]--- > [ 6411.451464] Kernel panic - not syncing: Oops - BUG: Fatal exception in interrupt > > Fixes: eb6ecbed0aa2 ("mm, thp: relax the VM_DENYWRITE constraint on file-backed THPs") > Suggested-by: Yang Shi > Signed-off-by: Xu Yu > Signed-off-by: Rongwei Wang Reviewed-by: Yang Shi > --- > mm/khugepaged.c | 7 ++++++- > 1 file changed, 6 insertions(+), 1 deletion(-) > > diff --git a/mm/khugepaged.c b/mm/khugepaged.c > index 045cc579f724..48de4e1b0783 100644 > --- a/mm/khugepaged.c > +++ b/mm/khugepaged.c > @@ -1763,6 +1763,10 @@ static void collapse_file(struct mm_struct *mm, > filemap_flush(mapping); > result = SCAN_FAIL; > goto xa_unlocked; > + } else if (PageWriteback(page)) { > + xas_unlock_irq(&xas); > + result = SCAN_FAIL; > + goto xa_unlocked; > } else if (trylock_page(page)) { > get_page(page); > xas_unlock_irq(&xas); > @@ -1798,7 +1802,8 @@ static void collapse_file(struct mm_struct *mm, > goto out_unlock; > } > > - if (!is_shmem && PageDirty(page)) { > + if (!is_shmem && (PageDirty(page) || > + PageWriteback(page))) { > /* > * khugepaged only works on read-only fd, so this > * page is dirty because it hasn't been flushed > -- > 2.27.0 > >