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AJvYcCU6cJzweSJIgYzrG6tugzU6RSFdiQTgNqSQrl1uSSeK2y3IORRLB5Tqt6bNFCTdnWx7vAJ3Ob1O2YiPtPghCLMGMW1D0wKa8mPIkz1LHg== X-Gm-Message-State: AOJu0YysFMYRXk/baI4c1km9Ri7452cvDI9LmgPPbiDs2FSG84/IIziu t4voFBuTmNC5RJgbwkUjbHCtOufVQWPB3bAcMzGjDmsfmAHOpIMOcDptv/M72CTAc02zYDy17Hs lBQ== X-Google-Smtp-Source: AGHT+IEY0dq37W/YL8K/UAYJglAS6s8iwOM7lJC17R20EwJUoGE14Vwyo3M1UA8Agcy0JGlj8awomXhRYvE= X-Received: from surenb-desktop.mtv.corp.google.com ([2620:15c:211:201:85f0:e3db:db05:85e2]) (user=surenb job=sendgmr) by 2002:a05:6902:18c9:b0:dcd:5e5d:458b with SMTP id ck9-20020a05690218c900b00dcd5e5d458bmr4001383ybb.3.1709749516858; Wed, 06 Mar 2024 10:25:16 -0800 (PST) Date: Wed, 6 Mar 2024 10:24:13 -0800 In-Reply-To: <20240306182440.2003814-1-surenb@google.com> Precedence: bulk X-Mailing-List: linux-modules@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20240306182440.2003814-1-surenb@google.com> X-Mailer: git-send-email 2.44.0.278.ge034bb2e1d-goog Message-ID: <20240306182440.2003814-16-surenb@google.com> Subject: [PATCH v5 15/37] lib: introduce early boot parameter to avoid page_ext memory overhead From: Suren Baghdasaryan To: akpm@linux-foundation.org Cc: kent.overstreet@linux.dev, mhocko@suse.com, vbabka@suse.cz, hannes@cmpxchg.org, roman.gushchin@linux.dev, mgorman@suse.de, dave@stgolabs.net, willy@infradead.org, liam.howlett@oracle.com, penguin-kernel@i-love.sakura.ne.jp, 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, jhubbard@nvidia.com, 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, aliceryhl@google.com, rientjes@google.com, minchan@google.com, kaleshsingh@google.com, surenb@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 The highest memory overhead from memory allocation profiling comes from page_ext objects. This overhead exists even if the feature is disabled but compiled-in. To avoid it, introduce an early boot parameter that prevents page_ext object creation. The new boot parameter is a tri-state with possible values of 0|1|never. When it is set to "never" the memory allocation profiling support is disabled, and overhead is minimized (currently no page_ext objects are allocated, in the future more overhead might be eliminated). As a result we also lose ability to enable memory allocation profiling at runtime (because there is no space to store alloctag references). Runtime sysctrl becomes read-only if the early boot parameter was set to "never". Note that the default value of this boot parameter depends on the CONFIG_MEM_ALLOC_PROFILING_ENABLED_BY_DEFAULT configuration. When CONFIG_MEM_ALLOC_PROFILING_ENABLED_BY_DEFAULT=n the boot parameter is set to "never", therefore eliminating any overhead. CONFIG_MEM_ALLOC_PROFILING_ENABLED_BY_DEFAULT=y results in boot parameter being set to 1 (enabled). This allows distributions to avoid any overhead by setting CONFIG_MEM_ALLOC_PROFILING_ENABLED_BY_DEFAULT=n config and with no changes to the kernel command line. We reuse sysctl.vm.mem_profiling boot parameter name in order to avoid introducing yet another control. This change turns it into a tri-state early boot parameter. Signed-off-by: Suren Baghdasaryan Reviewed-by: Vlastimil Babka --- lib/alloc_tag.c | 41 ++++++++++++++++++++++++++++++++++++++++- 1 file changed, 40 insertions(+), 1 deletion(-) diff --git a/lib/alloc_tag.c b/lib/alloc_tag.c index cb5adec4b2e2..617c2fbb6673 100644 --- a/lib/alloc_tag.c +++ b/lib/alloc_tag.c @@ -116,9 +116,46 @@ static bool alloc_tag_module_unload(struct codetag_type *cttype, return module_unused; } +#ifdef CONFIG_MEM_ALLOC_PROFILING_ENABLED_BY_DEFAULT +static bool mem_profiling_support __meminitdata = true; +#else +static bool mem_profiling_support __meminitdata; +#endif + +static int __init setup_early_mem_profiling(char *str) +{ + bool enable; + + if (!str || !str[0]) + return -EINVAL; + + if (!strncmp(str, "never", 5)) { + enable = false; + mem_profiling_support = false; + } else { + int res; + + res = kstrtobool(str, &enable); + if (res) + return res; + + mem_profiling_support = true; + } + + if (enable != static_key_enabled(&mem_alloc_profiling_key)) { + if (enable) + static_branch_enable(&mem_alloc_profiling_key); + else + static_branch_disable(&mem_alloc_profiling_key); + } + + return 0; +} +early_param("sysctl.vm.mem_profiling", setup_early_mem_profiling); + static __init bool need_page_alloc_tagging(void) { - return true; + return mem_profiling_support; } static __init void init_page_alloc_tagging(void) @@ -158,6 +195,8 @@ static int __init alloc_tag_init(void) if (IS_ERR_OR_NULL(alloc_tag_cttype)) return PTR_ERR(alloc_tag_cttype); + if (!mem_profiling_support) + memory_allocation_profiling_sysctls[0].mode = 0444; register_sysctl_init("vm", memory_allocation_profiling_sysctls); procfs_init();