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From: Kent Overstreet To: Suren Baghdasaryan Cc: Michal Hocko , akpm@linux-foundation.org, vbabka@suse.cz, 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, rostedt@goodmis.org, 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: <20240212213922.783301-1-surenb@google.com> <20240212213922.783301-32-surenb@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: X-Migadu-Flow: FLOW_OUT X-Rspamd-Server: rspam08 X-Rspamd-Queue-Id: 0F3E7C0011 X-Stat-Signature: oydtfs85whqnxnkjqdi375erkm6hoje3 X-Rspam-User: X-HE-Tag: 1708021792-2464 X-HE-Meta: U2FsdGVkX1+wJxTMVKY19Ip/eKDLhC8rqohjHvCVkb1xQMnKxzRLdaP5RCUKX3FAX4aVms6TjpuO/PnPpkWMbPEc9wnozpIGC4IaEhHytFnn2Y+bEFjiWBTJHX0K3FDD5n5sj4i9wi3R8gOJRZ2nPKGkR7C1yRA7jEMT2lQrwLMwQdOapNiCEx7W7veFz5n7asSG2jxsk8LodkFZFCsw9puDNtP4LdrtC2kgl9kw2T5XIdvMM6lT4iXljUTe8vFXzmgTExmJ7WR0RmRpBeLtOhou8spV4GJ138hDFcFnoSoL5AX+xl4kVDTkSW+0PvRytFVpttgA954IlM62wtfyfB+YaFOa7AUVVkKoHWlhfNYTgyRev5hBCobUAQIhtOsjm8yqM2ZK5GErgRfKHcgKIZuOzdp0tGqLnJHG1SUMzfGmSDkjafHYhMnimUwf5PCmF/8lp7DXY3WUlP9TgH+2Wnpdw1DQQzGgDLf9puStfOU7XAqNzdC+/xYfBogyiGzNHVR+ZPylSAPq1oCQLainiNjNkXFkML14Yyex1RrhBiptF5WtpLMViHygkoiKv0DfLRSq07AGGNtrrWETuxF6Dgt5OtEeZwUH7R2WBfLIk1HmYSgcdQ3rzFXHek7Hr7uom7j0LK0XfBBjyApxr39M76LGLWP/MQSszeqCv1YiIoFaAf5lG/Imu6kYtcJ013nedvgGCEe3zsvBMTG4+GnEEvGOz2j67xRTZJsUVVjnpRmT5ud7FuTqQ/GsZxrwYgBb/afkm9RnJaWzAVjee1UFfLDWTd1YLzfy2GzCgry1vpjq7yWIEIyrotf8TVYCAKC8DfiDugziZfMoRJa4+N+7KMPG/+GsujBPOzLMfGbqIWWG3Xeq0lsH2jZigw32SQsSbvDWm379Gakv6fH5/0rzXZgueM16XWBheeR1/ryZYbrmDuTzefDfanddUyTKFZApeB5gDCH9je8LdkdrMl5 MuVE+3Me QyJ4g2LQWhqfCtfDX+hoTMFyKxX9YJDDVCbaGffJjF0HU3YB7KnFFefR+O0/RHOD+NK88UqMvvC4/gJomYTNrFEpV9jjc6cHgXe0YMYya6dpwH5gafkZEL/lKFCfQ3KZU/P+SkG3TUPpqpsF/7f5eC08pgyoxgaVhSiCmJtKHrlPWiPixqLds84kmq3oT74wnNMVMWKK2k0mw1RfQEfhKtexNQGLRUOT6I2ge/c2mIm0oHv62kEfpIpxBjqFKXNpTdPwIUzMy54e9Yp9T30GX2KOrMeB0ZoKYhVE6 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: List-Subscribe: List-Unsubscribe: On Thu, Feb 15, 2024 at 08:47:59AM -0800, Suren Baghdasaryan wrote: > On Thu, Feb 15, 2024 at 8:45 AM Michal Hocko wrote: > > > > On Thu 15-02-24 06:58:42, Suren Baghdasaryan wrote: > > > On Thu, Feb 15, 2024 at 1:22 AM Michal Hocko wrote: > > > > > > > > On Mon 12-02-24 13:39:17, Suren Baghdasaryan wrote: > > > > [...] > > > > > @@ -423,4 +424,18 @@ void __show_mem(unsigned int filter, nodemask_t *nodemask, int max_zone_idx) > > > > > #ifdef CONFIG_MEMORY_FAILURE > > > > > printk("%lu pages hwpoisoned\n", atomic_long_read(&num_poisoned_pages)); > > > > > #endif > > > > > +#ifdef CONFIG_MEM_ALLOC_PROFILING > > > > > + { > > > > > + struct seq_buf s; > > > > > + char *buf = kmalloc(4096, GFP_ATOMIC); > > > > > + > > > > > + if (buf) { > > > > > + printk("Memory allocations:\n"); > > > > > + seq_buf_init(&s, buf, 4096); > > > > > + alloc_tags_show_mem_report(&s); > > > > > + printk("%s", buf); > > > > > + kfree(buf); > > > > > + } > > > > > + } > > > > > +#endif > > > > > > > > I am pretty sure I have already objected to this. Memory allocations in > > > > the oom path are simply no go unless there is absolutely no other way > > > > around that. In this case the buffer could be preallocated. > > > > > > Good point. We will change this to a smaller buffer allocated on the > > > stack and will print records one-by-one. Thanks! > > > > __show_mem could be called with a very deep call chains. A single > > pre-allocated buffer should just do ok. > > Ack. Will do. No, we're not going to permanently burn 4k here. It's completely fine if the allocation fails, there's nothing "unsafe" about doing a GFP_ATOMIC allocation here.