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AJvYcCXXNgXK4G5l+uZQR+Ywzip4NVbRW6050Po4teuE8kYdyjEiqX+lkfABKjXROWvu1UOG4aflchYpDO+IbK926nNJbOa1ywq+p41Cj7B+Kg== X-Gm-Message-State: AOJu0YwmN8M8O4MbCVyM8RcyT7jodIhekx5MkWJhQk7Eh7mFkC36cv2w n27Rbp30in+0R581ozFM/oK2OvVsI/dlOHtCqGjnYLUyAsxEtjMMw6ikxK9Rpoqd7qEQXAKntE/ yNg== X-Google-Smtp-Source: AGHT+IFQIptCkWW78zp6nNtKkGuc5SIQRmDLhLOqGJHxbi7rcmsMoDf48+EiK0QB4NL+su2PCoHiqX08ucE= X-Received: from surenb-desktop.mtv.corp.google.com ([2620:15c:211:201:85f0:e3db:db05:85e2]) (user=surenb job=sendgmr) by 2002:a05:690c:fcd:b0:609:33af:cca8 with SMTP id dg13-20020a05690c0fcd00b0060933afcca8mr4422200ywb.2.1709749527811; Wed, 06 Mar 2024 10:25:27 -0800 (PST) Date: Wed, 6 Mar 2024 10:24:18 -0800 In-Reply-To: <20240306182440.2003814-1-surenb@google.com> Precedence: bulk X-Mailing-List: linux-fsdevel@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: <20240306182440.2003814-21-surenb@google.com> Subject: [PATCH v5 20/37] mm: fix non-compound multi-order memory accounting in __free_pages 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 When a non-compound multi-order page is freed, it is possible that a speculative reference keeps the page pinned. In this case we free all pages except for the first page, which will be freed later by the last put_page(). However put_page() ignores the order of the page being freed, treating it as a 0-order page. This creates a memory accounting imbalance because the pages freed in __free_pages() do not have their own alloc_tag and their memory was accounted to the first page. To fix this the first page should adjust its allocation size counter when "tail" pages are freed. Reported-by: Vlastimil Babka Signed-off-by: Suren Baghdasaryan Reviewed-by: Vlastimil Babka --- include/linux/pgalloc_tag.h | 24 ++++++++++++++++++++++++ mm/page_alloc.c | 11 ++++++++++- 2 files changed, 34 insertions(+), 1 deletion(-) diff --git a/include/linux/pgalloc_tag.h b/include/linux/pgalloc_tag.h index 9e6ad8e0e4aa..59de43172cc2 100644 --- a/include/linux/pgalloc_tag.h +++ b/include/linux/pgalloc_tag.h @@ -96,12 +96,36 @@ static inline void pgalloc_tag_split(struct page *page, unsigned int nr) page_ext_put(page_ext); } +static inline struct alloc_tag *pgalloc_tag_get(struct page *page) +{ + struct alloc_tag *tag = NULL; + + if (mem_alloc_profiling_enabled()) { + union codetag_ref *ref = get_page_tag_ref(page); + + alloc_tag_sub_check(ref); + if (ref && ref->ct) + tag = ct_to_alloc_tag(ref->ct); + put_page_tag_ref(ref); + } + + return tag; +} + +static inline void pgalloc_tag_sub_bytes(struct alloc_tag *tag, unsigned int order) +{ + if (mem_alloc_profiling_enabled() && tag) + this_cpu_sub(tag->counters->bytes, PAGE_SIZE << order); +} + #else /* CONFIG_MEM_ALLOC_PROFILING */ static inline void pgalloc_tag_add(struct page *page, struct task_struct *task, unsigned int order) {} static inline void pgalloc_tag_sub(struct page *page, unsigned int order) {} static inline void pgalloc_tag_split(struct page *page, unsigned int nr) {} +static inline struct alloc_tag *pgalloc_tag_get(struct page *page) { return NULL; } +static inline void pgalloc_tag_sub_bytes(struct alloc_tag *tag, unsigned int order) {} #endif /* CONFIG_MEM_ALLOC_PROFILING */ diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 39dc4dcf14f5..b402149a795f 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -4697,12 +4697,21 @@ void __free_pages(struct page *page, unsigned int order) { /* get PageHead before we drop reference */ int head = PageHead(page); + struct alloc_tag *tag = pgalloc_tag_get(page); if (put_page_testzero(page)) free_the_page(page, order); else if (!head) - while (order-- > 0) + while (order-- > 0) { free_the_page(page + (1 << order), order); + /* + * non-compound multi-order page accounts all allocations + * to the first page (just like compound one), therefore + * we need to adjust the allocation size of the first + * page as its order is ignored when put_page() frees it. + */ + pgalloc_tag_sub_bytes(tag, order); + } } EXPORT_SYMBOL(__free_pages);