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[73.219.103.14]) by smtp.gmail.com with ESMTPSA id t12-20020a05622a01cc00b002f204a559a4sm2200957qtw.53.2022.04.22.17.46.08 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 22 Apr 2022 17:46:09 -0700 (PDT) Date: Fri, 22 Apr 2022 20:46:07 -0400 From: Kent Overstreet To: Roman Gushchin Cc: Michal Hocko , linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, hch@lst.de, hannes@cmpxchg.org, akpm@linux-foundation.org, linux-clk@vger.kernel.org, linux-tegra@vger.kernel.org, linux-input@vger.kernel.org, rostedt@goodmis.org Subject: Re: [PATCH v2 8/8] mm: Centralize & improve oom reporting in show_mem.c Message-ID: <20220423004607.q4lbz2mplkhlbyhm@moria.home.lan> References: <20220421234837.3629927-1-kent.overstreet@gmail.com> <20220421234837.3629927-14-kent.overstreet@gmail.com> <20220422234820.plusgyixgybebfmi@moria.home.lan> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Stat-Signature: 944ubjyq1zf4emi7k55trdja8ura7a5x Authentication-Results: imf12.hostedemail.com; dkim=pass header.d=gmail.com header.s=20210112 header.b=DoTALWV0; spf=pass (imf12.hostedemail.com: domain of kent.overstreet@gmail.com designates 209.85.222.175 as permitted sender) smtp.mailfrom=kent.overstreet@gmail.com; dmarc=pass (policy=none) header.from=gmail.com X-Rspam-User: X-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: D454440022 X-HE-Tag: 1650674765-22691 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 Fri, Apr 22, 2022 at 05:27:41PM -0700, Roman Gushchin wrote: > You're scanning over a small portion of all shrinker lists (on a machine with > cgroups), so the top-10 list has little value. > Global ->count_objects() return the number of objects on the system/root_mem_cgroup > level, not the shrinker's total. Not quite following what you're saying here...? If you're complaining that my current top-10-shrinker report isn't memcg aware, that's valid - I can fix that. > > In my experience, it's rare to be _so_ out of memory that small kmalloc > > allocations are failing - we'll be triggering the show_mem() report before that > > happens. > > I agree. However the OOM killer _has_ to make the progress even in such rare > circumstances. Oh, and the concern is allocator recursion? Yeah, that's a good point. Do you know if using memalloc_noreclaim_(save|restore) is sufficient for that, or do we want GFP_ATOMIC? I'm already using GFP_ATOMIC for allocations when we generate the report on slabs, since we're taking the slab mutex there.