linux-kernel - [PATCH v5 20/37] mm: fix non-compound multi-order memory accounting in __free

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20240306182440.2003814-21-surenb@google.com>
Date: Wed,  6 Mar 2024 10:24:18 -0800
From: Suren Baghdasaryan <surenb@...gle.com>
To: akpm@...ux-foundation.org
Cc: kent.overstreet@...ux.dev, mhocko@...e.com, vbabka@...e.cz, 
	hannes@...xchg.org, roman.gushchin@...ux.dev, mgorman@...e.de, 
	dave@...olabs.net, willy@...radead.org, liam.howlett@...cle.com, 
	penguin-kernel@...ove.sakura.ne.jp, corbet@....net, void@...ifault.com, 
	peterz@...radead.org, juri.lelli@...hat.com, catalin.marinas@....com, 
	will@...nel.org, arnd@...db.de, tglx@...utronix.de, mingo@...hat.com, 
	dave.hansen@...ux.intel.com, x86@...nel.org, peterx@...hat.com, 
	david@...hat.com, axboe@...nel.dk, mcgrof@...nel.org, masahiroy@...nel.org, 
	nathan@...nel.org, dennis@...nel.org, jhubbard@...dia.com, tj@...nel.org, 
	muchun.song@...ux.dev, rppt@...nel.org, paulmck@...nel.org, 
	pasha.tatashin@...een.com, yosryahmed@...gle.com, yuzhao@...gle.com, 
	dhowells@...hat.com, hughd@...gle.com, andreyknvl@...il.com, 
	keescook@...omium.org, ndesaulniers@...gle.com, vvvvvv@...gle.com, 
	gregkh@...uxfoundation.org, ebiggers@...gle.com, ytcoode@...il.com, 
	vincent.guittot@...aro.org, dietmar.eggemann@....com, rostedt@...dmis.org, 
	bsegall@...gle.com, bristot@...hat.com, vschneid@...hat.com, cl@...ux.com, 
	penberg@...nel.org, iamjoonsoo.kim@....com, 42.hyeyoo@...il.com, 
	glider@...gle.com, elver@...gle.com, dvyukov@...gle.com, shakeelb@...gle.com, 
	songmuchun@...edance.com, jbaron@...mai.com, aliceryhl@...gle.com, 
	rientjes@...gle.com, minchan@...gle.com, kaleshsingh@...gle.com, 
	surenb@...gle.com, kernel-team@...roid.com, linux-doc@...r.kernel.org, 
	linux-kernel@...r.kernel.org, iommu@...ts.linux.dev, 
	linux-arch@...r.kernel.org, linux-fsdevel@...r.kernel.org, linux-mm@...ck.org, 
	linux-modules@...r.kernel.org, kasan-dev@...glegroups.com, 
	cgroups@...r.kernel.org
Subject: [PATCH v5 20/37] mm: fix non-compound multi-order memory accounting
 in __free_pages

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 <vbabka@...e.cz>
Signed-off-by: Suren Baghdasaryan <surenb@...gle.com>
---
 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);
 
-- 
2.44.0.278.ge034bb2e1d-goog