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[82.17.115.212]) by smtp.gmail.com with ESMTPSA id f16sm2950825wrm.47.2021.05.20.04.42.58 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 20 May 2021 04:42:58 -0700 (PDT) Date: Thu, 20 May 2021 12:42:57 +0100 From: Aaron Tomlin To: Vlastimil Babka Cc: Andrew Morton , linux-mm@kvack.org, mhocko@suse.com, willy@infradead.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v3] mm/page_alloc: bail out on fatal signal during reclaim/compaction retry attempt Message-ID: <20210520114257.huqhkqsdrhohn3u5@ava.usersys.com> X-PGP-Key: http://pgp.mit.edu/pks/lookup?search=atomlin%40redhat.com X-PGP-Fingerprint: 7906 84EB FA8A 9638 8D1E 6E9B E2DE 9658 19CC 77D6 References: <20210519201743.3260890-1-atomlin@redhat.com> <20210519213455.97ff95f0124b4120787f8314@linux-foundation.org> <9b11dcd8-bc3b-aae9-feb1-43543bf9e22f@suse.cz> MIME-Version: 1.0 In-Reply-To: <9b11dcd8-bc3b-aae9-feb1-43543bf9e22f@suse.cz> X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="p5hnecwugz7gnprh" Content-Disposition: inline Authentication-Results: imf01.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=egxZCuBi; dmarc=pass (policy=none) header.from=redhat.com; spf=none (imf01.hostedemail.com: domain of atomlin@redhat.com has no SPF policy when checking 216.205.24.124) smtp.mailfrom=atomlin@redhat.com X-Stat-Signature: 3kgx4tkndwtwwif6ihwfxmjj538jmedj X-Rspamd-Queue-Id: 7A5EC5001652 X-Rspamd-Server: rspam02 X-HE-Tag: 1621510983-242012 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: --p5hnecwugz7gnprh Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Thu 2021-05-20 12:20 +0200, Vlastimil Babka wrote: > On 5/20/21 6:34 AM, Andrew Morton wrote: > >=20 > > What observed problems motivated this change? > >=20 > > What were the observed runtime effects of this change? >=20 > Yep those details from the previous thread should be included here. Fair enough. During kernel crash dump/or vmcore analysis: I discovered in the context of __alloc_pages_slowpath() the value stored in the no_progress_loops variable was found to be 31,611,688 i.e. well above MAX_RECLAIM_RETRIES; and a fatal signal was pending against current. #6 [ffff00002e78f7c0] do_try_to_free_pages+0xe4 at ffff00001028bd24 #7 [ffff00002e78f840] try_to_free_pages+0xe4 at ffff00001028c0f4 #8 [ffff00002e78f900] __alloc_pages_nodemask+0x500 at ffff0000102cd130 // w28 = =3D *(sp + 148) /* no_progress_loops */ 0xffff0000102cd1e0 <__alloc_pages_nodemask+0x5b0>: ldr w0, [s= p,#148] // w0 =3D= w0 + 0x1 0xffff0000102cd1e4 <__alloc_pages_nodemask+0x5b4>: add w0, w0= , #0x1 // *(sp += 148) =3D w0 0xffff0000102cd1e8 <__alloc_pages_nodemask+0x5b8>: str w0, [s= p,#148] // if (w0= >=3D 0x10) // go= to __alloc_pages_nodemask+0x904 0xffff0000102cd1ec <__alloc_pages_nodemask+0x5bc>: cmp w0, #0= x10 0xffff0000102cd1f0 <__alloc_pages_nodemask+0x5c0>: b.gt 0xffff= 0000102cd534 - The stack pointer was 0xffff00002e78f900 crash> p *(int *)(0xffff00002e78f900+148) $1 =3D 31611688 crash> ps 521171 PID PPID CPU TASK ST %MEM VSZ RSS COMM > 521171 1 36 ffff8080e2128800 RU 0.0 34789440 18624 speci= al crash> p &((struct task_struct *)0xffff8080e2128800)->signal.shared_pe= nding $2 =3D (struct sigpending *) 0xffff80809a416e40 crash> p ((struct sigpending *)0xffff80809a416e40)->signal.sig[0] $3 =3D 0x804100 crash> sig -s 0x804100 SIGKILL SIGTERM SIGXCPU crash> p ((struct sigpending *)0xffff80809a416e40)->signal.sig[0] & 1U= << (9 - 1) $4 =3D 0x100 Unfortunately, this incident was not reproduced, to date. Kind regards, --=20 Aaron Tomlin --p5hnecwugz7gnprh Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQIzBAABCAAdFiEEeQaE6/qKljiNHm6b4t6WWBnMd9YFAmCmSzsACgkQ4t6WWBnM d9YBLBAAoJRnCKOIc23LwajJoo5uFmSIWFNDG9YM0/iHSaiWQNA5zBCqa3VtINlS ORjeBzihiNP/juBqX6YRUQ1C+BjA+Rcw7tSyFLhoxmmgE9Zha+saLlCZUOTruqCz oTbAcLi8D3vGW4NP6MMLjl5RFPsmiqHluUOpMXUQ2J2UEeJzfU2IUZl32HgP8TA5 ofQHyCvaKrLnmMmioxNuuxzXsNH0kpd5oRhDABTEjokOlCmKcXeB7npEQP1rf3xB dGdGF4Nra3W5m+eNolpomdoYGNDaCJ3k/UFnomXyPk0hFknJ6Ijy5tpVT2eqmS8v 1Qo6UTwLoPu6cjtXD5mccCTX85RVxUYSNAA8I4omR8uQyN3OgSt8LEKUjSb3j9YM CkoEKPzb6hLUt9za2PMGmaCd54rYX4irwvXVJgzWE70bQw6g6FFRwQLIKc4sSQzD Jg7t2QN5BPsMyAwJg4wdYdrKq/WthdcmldU3cJ104/BJSFOomyZiTI911X7T3QvY tG7/uvStfw/3vWI5YeX4p2DrjSzoU+flE95rgTd6z/hWCk4F4ELdwSJoCPgsWa6t 1lpA5OAG1RElhtqcfeCU2xM1v3Yc3TpkD6KzI0RqlybEMCRQdkFlQzCZGPd5RfSq s6Z/MKHyi/rlW6DFe+CK2+6v7Tw3GR02wr1acAfhcAI3DO1hhdU= =r3HN -----END PGP SIGNATURE----- --p5hnecwugz7gnprh--