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Tue, 20 Feb 2024 16:23:34 +0000 (UTC) Received: from dovecot-director2.suse.de ([2a07:de40:b281:106:10:150:64:167]) by imap1.dmz-prg2.suse.org with ESMTPSA id Dr6rHAbS1GVrVAAAD6G6ig (envelope-from ); Tue, 20 Feb 2024 16:23:34 +0000 Date: Tue, 20 Feb 2024 17:23:29 +0100 From: Michal Hocko To: Suren Baghdasaryan Cc: Kent Overstreet , Steven Rostedt , Vlastimil Babka , akpm@linux-foundation.org, hannes@cmpxchg.org, roman.gushchin@linux.dev, mgorman@suse.de, dave@stgolabs.net, willy@infradead.org, liam.howlett@oracle.com, corbet@lwn.net, void@manifault.com, peterz@infradead.org, juri.lelli@redhat.com, catalin.marinas@arm.com, will@kernel.org, arnd@arndb.de, tglx@linutronix.de, mingo@redhat.com, dave.hansen@linux.intel.com, x86@kernel.org, peterx@redhat.com, david@redhat.com, axboe@kernel.dk, mcgrof@kernel.org, masahiroy@kernel.org, nathan@kernel.org, dennis@kernel.org, tj@kernel.org, muchun.song@linux.dev, rppt@kernel.org, paulmck@kernel.org, pasha.tatashin@soleen.com, yosryahmed@google.com, yuzhao@google.com, dhowells@redhat.com, hughd@google.com, andreyknvl@gmail.com, keescook@chromium.org, ndesaulniers@google.com, vvvvvv@google.com, gregkh@linuxfoundation.org, ebiggers@google.com, ytcoode@gmail.com, vincent.guittot@linaro.org, dietmar.eggemann@arm.com, bsegall@google.com, bristot@redhat.com, vschneid@redhat.com, cl@linux.com, penberg@kernel.org, iamjoonsoo.kim@lge.com, 42.hyeyoo@gmail.com, glider@google.com, elver@google.com, dvyukov@google.com, shakeelb@google.com, songmuchun@bytedance.com, jbaron@akamai.com, rientjes@google.com, minchan@google.com, kaleshsingh@google.com, kernel-team@android.com, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, iommu@lists.linux.dev, linux-arch@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-modules@vger.kernel.org, kasan-dev@googlegroups.com, cgroups@vger.kernel.org Subject: Re: [PATCH v3 31/35] lib: add memory allocations report in show_mem() Message-ID: References: <320cd134-b767-4f29-869b-d219793ba8a1@suse.cz> <20240215180742.34470209@gandalf.local.home> <20240215181648.67170ed5@gandalf.local.home> <20240215182729.659f3f1c@gandalf.local.home> Precedence: bulk X-Mailing-List: linux-arch@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; 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RCVD_TLS_ALL(0.00)[]; SUSPICIOUS_RECIPS(1.50)[] X-Rspamd-Server: rspamd1.dmz-prg2.suse.org X-Spam-Score: 1.68 X-Rspamd-Queue-Id: ABB6921EFF X-Spam-Level: * X-Spam-Flag: NO X-Spamd-Bar: + On Mon 19-02-24 09:17:36, Suren Baghdasaryan wrote: [...] > For now I think with Vlastimil's __GFP_NOWARN suggestion the code > becomes safe and the only risk is to lose this report. If we get cases > with reports missing this data, we can easily change to reserved > memory. This is not just about missing part of the oom report. This is annoying but not earth shattering. Eating into very small reserves (that might be the only usable memory while the system is struggling in OOM situation) could cause functional problems that would be non trivial to test for. All that for debugging purposes is just lame. If you want to reuse the code for a different purpose then abstract it and allocate the buffer when you can afford that and use preallocated on when in OOM situation. We have always went extra mile to avoid potentially disruptive operations from the oom handling code and I do not see any good reason to diverge from that principle. -- Michal Hocko SUSE Labs