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Sun, 3 May 2020 04:44:49 -0400 (EDT) Received: from vostro.rath.org (vostro [192.168.12.4]) by ebox.rath.org (Postfix) with ESMTPS id 2AF56B4; Sun, 3 May 2020 08:44:48 +0000 (UTC) Received: by vostro.rath.org (Postfix, from userid 1000) id A0922E012A; Sun, 3 May 2020 09:43:41 +0100 (BST) From: Nikolaus Rath To: Matthew Wilcox Cc: linux-fsdevel@vger.kernel.org, fuse-devel , linux-mm , miklos , Gabriel Krisman Bertazi , =?utf-8?Q?Andr=C3=A9?= Almeida Subject: Re: [fuse-devel] fuse: trying to steal weird page References: <87a72qtaqk.fsf@vostro.rath.org> <877dxut8q7.fsf@vostro.rath.org> <20200503032613.GE29705@bombadil.infradead.org> Mail-Copies-To: never Mail-Followup-To: Matthew Wilcox , linux-fsdevel@vger.kernel.org, fuse-devel , linux-mm , miklos , Gabriel Krisman Bertazi , =?utf-8?Q?Andr=C3=A9?= Almeida Date: Sun, 03 May 2020 09:43:41 +0100 In-Reply-To: <20200503032613.GE29705@bombadil.infradead.org> (Matthew Wilcox's message of "Sat, 2 May 2020 20:26:13 -0700") Message-ID: <87368hz9vm.fsf@vostro.rath.org> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/26.1 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable 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: On May 02 2020, Matthew Wilcox wrote: > On Sat, May 02, 2020 at 08:52:48PM +0100, Nikolaus Rath wrote: >> On May 02 2020, Nikolaus Rath wrote: >> > I have recently noticed that a FUSE filesystem regularly produces many >> > kernel messages like this: >> > >> > [ 2333.009931] fuse: trying to steal weird page >> > [ 2333.009937] fuse: page=3D00000000dd1750e3 index=3D2022240 flags=3D1= 7ffffc0000097, count=3D1, >> > mapcount=3D0, mapping=3D00000000125079ad > ... >> > What are the implications of the above kernel message? Is there a way = to >> > provide more debugging information? > > It'd be helpful to use the common debugging infrastructure which prints > more useful information: > > +++ b/fs/fuse/dev.c > @@ -772,8 +772,7 @@ static int fuse_check_page(struct page *page) > 1 << PG_lru | > 1 << PG_active | > 1 << PG_reclaim))) { > - pr_warn("trying to steal weird page\n"); > - pr_warn(" page=3D%p index=3D%li flags=3D%08lx, count=3D%= i, mapcount=3D%i, mapping=3D%p\n", page, page->index, page->flags, page_cou= nt(page), page_mapcount(page), page->mapping); > + dump_page(page, "fuse: trying to steal weird page"); > return 1; > } > return 0; > > (whitespace damaged; if you can't make the equivalent change, let me > know and I'll send you a real patch) Here's what I got: [ 221.277260] page:ffffec4bbd639880 refcount:1 mapcount:0 mapping:00000000= 00000000 index:0xd9 [ 221.277265] flags: 0x17ffffc0000097(locked|waiters|referenced|uptodate|l= ru) [ 221.277269] raw: 0017ffffc0000097 ffffec4bbd62f048 ffffec4bbd619308 0000= 000000000000 [ 221.277271] raw: 00000000000000d9 0000000000000000 00000001ffffffff ffff= 9aec11beb000 [ 221.277272] page dumped because: fuse: trying to steal weird page [ 221.277273] page->mem_cgroup:ffff9aec11beb000 [ 221.601910] page:ffffec4bbd4b2dc0 refcount:1 mapcount:0 mapping:00000000= 00000000 index:0x1273 [ 221.601915] flags: 0x17ffffc0000097(locked|waiters|referenced|uptodate|l= ru) [ 221.601919] raw: 0017ffffc0000097 ffffec4bbd51f488 ffffec4bbd4b2d48 0000= 000000000000 [ 221.601921] raw: 0000000000001273 0000000000000000 00000001ffffffff ffff= 9aec11beb000 [ 221.601922] page dumped because: fuse: trying to steal weird page [ 221.601923] page->mem_cgroup:ffff9aec11beb000 [ 221.958699] page:ffffec4bbd424d80 refcount:1 mapcount:0 mapping:00000000= 00000000 index:0x38be [ 221.958703] flags: 0x17ffffc0000097(locked|waiters|referenced|uptodate|l= ru) [ 221.958707] raw: 0017ffffc0000097 ffffec4bbd424048 ffffec4bbd424d48 0000= 000000000000 [ 221.958709] raw: 00000000000038be 0000000000000000 00000001ffffffff ffff= 9aec11beb000 [ 221.958710] page dumped because: fuse: trying to steal weird page [ 221.958711] page->mem_cgroup:ffff9aec11beb000 Best, -Nikolaus --=20 GPG Fingerprint: ED31 791B 2C5C 1613 AF38 8B8A D113 FCAC 3C4E 599F =C2=BBTime flies like an arrow, fruit flies like a Banana.=C2= =AB