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[82.17.115.212]) by smtp.gmail.com with ESMTPSA id r11sm440744wrp.46.2021.05.19.12.48.29 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 19 May 2021 12:48:29 -0700 (PDT) Date: Wed, 19 May 2021 20:48:29 +0100 From: Aaron Tomlin To: Matthew Wilcox Cc: linux-mm@kvack.org, akpm@linux-foundation.org, vbabka@suse.cz, mhocko@suse.com, linux-kernel@vger.kernel.org Subject: Re: [PATCH v2] mm/page_alloc: bail out on fatal signal during reclaim/compaction retry attempt Message-ID: <20210519194829.sess6lhfzlmccpdu@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: <20210519192321.3247175-1-atomlin@redhat.com> MIME-Version: 1.0 In-Reply-To: X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Disposition: inline X-Rspamd-Queue-Id: 9D23920007F0 Authentication-Results: imf28.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=glVi1EL0; dmarc=pass (policy=none) header.from=redhat.com; spf=none (imf28.hostedemail.com: domain of atomlin@redhat.com has no SPF policy when checking 170.10.133.124) smtp.mailfrom=atomlin@redhat.com X-Rspamd-Server: rspam03 X-Stat-Signature: mq5ghhka173hr5yg4kqg5xi6uyo5nzxx X-HE-Tag: 1621453712-954770 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 Wed 2021-05-19 20:32 +0100, Matthew Wilcox wrote: > On Wed, May 19, 2021 at 08:23:21PM +0100, Aaron Tomlin wrote: > > +++ b/mm/page_alloc.c > > @@ -4252,6 +4252,9 @@ should_compact_retry(struct alloc_context *ac, int order, int alloc_flags, > > if (!order) > > return false; > > > > + if (fatal_signal_pending(current)) > > + goto out; > > I think 'goto out' will be confusing. It'll output a tracepoint, which > isn't going to record that a fatal signal is pending, so it'll cause > some head scratching for someone looking through the traces. I > think we should just return false here and skip the tracepoint. I agree. Having said this, I do plan to send a patch to illustrate why compaction should not retry to avoid possible confusion. Nevertheless, I am happy to modify as per your request. Kind regards, -- Aaron Tomlin