From nobody Sun Dec 14 19:13:36 2025 Received: from mail-qk1-f181.google.com (mail-qk1-f181.google.com [209.85.222.181]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 7710A21660B; Thu, 12 Dec 2024 18:33:56 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.222.181 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1734028438; cv=none; b=u5e6imOV3SC87kfkMv/F9g39qXPntSptGo/yWAChnGH4XBBMFWGSj66xn9skOJOl2l/cgQGu+YtGS3S/duhnsq8CNHNsXy1lEju/4TV9+B2lqB5BSlOOFf/PyVTn0NKieYd+ejJrYQTPP6N7kcDnJQ+AmmIkl57YyGCLTcPFlmg= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1734028438; c=relaxed/simple; bh=tZsu8TiuLR0S0KrbV0gJ11FoB48CVZZWePFjnRlLhIs=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=UqRQywU8+gyQwTsaRwj/URDSSrQ0J7fqThsd1rj7MXxwuyNyGYghNUfbXtcQUcyCvLQRCRreS8LDSZEYq1i3aB4ppWSQocIM/Nao6dX3z69Kl0ZBc4j2eadeuD27i86zG7z5bAzQn27nM2XAYXSkF4gmh9NFE7sxMgbnqHlPWN4= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b=YIvDhbLJ; arc=none smtp.client-ip=209.85.222.181 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="YIvDhbLJ" Received: by mail-qk1-f181.google.com with SMTP id af79cd13be357-7b6f8524f23so55800785a.2; Thu, 12 Dec 2024 10:33:56 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1734028435; x=1734633235; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:from:to:cc:subject:date:message-id:reply-to; bh=ZqbWz5w80/Ao2+q+hylk/EZt96xoYzXRfCQenTqI3gE=; b=YIvDhbLJTZSOmwqPVFp+0cCUWmLYyQaJ24rd1MkCOPyYO6Kbvnq0ISR4ntcKA2qfxe 4xTC2XYVyAxLX6hwF5IkWGEO5qHYOsf2ljCn9LouHQ3JH58fSYyMiU02JlFIvT4aHu1L bAE/pWP8C492opvRB+7VkZuuZ52/sdoClgjGt5lvRyvAlkIqeKooOevr4EaPSKicdVkU pGO5ZI3bShB7BEoASU+Kh3OvhRicsvoetl3HtQNnWKSadmMdyWWf88Z9Xb9NlU8zv4iX sPoCoyCbnTJZLcL9RKPh/X7JB9N5dlt90HcV44z05WjGXfxL9gTj2qegamHSgaMX9t1h JINA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1734028435; x=1734633235; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=ZqbWz5w80/Ao2+q+hylk/EZt96xoYzXRfCQenTqI3gE=; b=kHxR9zWqbDre3DylVKsCL/RYcWbHkwmYwm/OrS8c/mpVgEEpKxY+IkbvD1+Od9Qt6r Z2YVWaY3Zqy+v8IsLloRhRINJL9VU6TJris402gZKD6xRcHV9KsoTtL9HlWURuP6Dni9 yLDmNaybZuwS3Xam6RnaHQXGTBWKm4m0sN/WgTaQ0mT5AwHHHhEcbdJQSU4JK5mJ+n2W XsjoSluP7iMHCYWtPit+UlzbXNY87rlG0zdZNR5ees9tf8+NDFrCNpzSIv632i6slem5 9ogGF6KBsNXkGEvs458zmaIQSBq50QZ2buUWCTXL2YraUxvb14dbrOk3EC4TizW3E2m/ 4tIA== X-Forwarded-Encrypted: i=1; AJvYcCVD6BpkMNztMwuWUW3o9/lBWRlkLB4Gk4uJsGbnSHw+j36/58MnaR+N9spT1eo96vqtiQnpecJz@vger.kernel.org, AJvYcCWGmmhgsO+FCCXG5wkuOoi1hJOOvlEjeoWefp45AahHC2v/SbL6OQl2KLrImu0J8xrG1B6lKgPeN9MIOtY=@vger.kernel.org X-Gm-Message-State: AOJu0YxTAui903q3k9ZHnsMHB4GyhUzajRqSnFjfjKj6m/tdkPHtqtDa 2YJcUCzNJHWNr2NNAPm3ryFat1tCi2ggGQTuLDcOXn3uCpHRvMxg X-Gm-Gg: ASbGncuu5oOuojFWFhGOEtfz+PDyUkEXrAonEoVGKZ0oa+J5/MJwkvukfAeln1lj/sT BLPQmtkYmaM2c0JfT+ph/2GBRmvI4KhiEXH4vN9N1jgNuVU4/F+zsjZlFS9DXLnZMoStSv/vpGR SyhzIkfCMObAh9eDdy7IDePhPNoIJ2lCWpY3hGlmJUp8EvOWMVou8vyzWGrIb+Z0nivSKqy1qw9 Pd01FTiKVEk54PAIyYfDtdjo5fPaCPe9yS2mG5QKOJ9Ay0Yt+LPRw== X-Google-Smtp-Source: AGHT+IHW4lqyDD/WZ9MZc2ZAevw778ZC2oWLKzpYfIVQPXRhxGqN/JXNrTHqvV6y9ff/9LhoNEnlKQ== X-Received: by 2002:a05:620a:40c8:b0:7b6:f110:43d5 with SMTP id af79cd13be357-7b6f893016amr223205185a.18.1734028435127; Thu, 12 Dec 2024 10:33:55 -0800 (PST) Received: from localhost ([2a03:2880:20ff:c::]) by smtp.gmail.com with ESMTPSA id af79cd13be357-7b6eed3d22dsm157188685a.31.2024.12.12.10.33.53 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 12 Dec 2024 10:33:54 -0800 (PST) From: Usama Arif To: david@redhat.com, akpm@linux-foundation.org, linux-mm@kvack.org Cc: hannes@cmpxchg.org, riel@surriel.com, shakeel.butt@linux.dev, roman.gushchin@linux.dev, yuzhao@google.com, npache@redhat.com, baohua@kernel.org, ryan.roberts@arm.com, rppt@kernel.org, willy@infradead.org, cerasuolodomenico@gmail.com, ryncsn@gmail.com, corbet@lwn.net, linux-kernel@vger.kernel.org, kernel-team@meta.com, Usama Arif , stable@vger.kernel.org Subject: [PATCH v2] mm: convert partially_mapped set/clear operations to be atomic Date: Thu, 12 Dec 2024 18:33:51 +0000 Message-ID: <20241212183351.1345389-1-usamaarif642@gmail.com> X-Mailer: git-send-email 2.43.5 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Other page flags in the 2nd page, like PG_hwpoison and PG_anon_exclusive can get modified concurrently. Changes to other page flags might be lost if they are happening at the same time as non-atomic partially_mapped operations. Hence, make partially_mapped operations atomic. Fixes: 8422acdc97ed ("mm: introduce a pageflag for partially mapped folios") Cc: stable@vger.kernel.org Reported-by: David Hildenbrand Link: https://lore.kernel.org/all/e53b04ad-1827-43a2-a1ab-864c7efecf6e@redh= at.com/ Signed-off-by: Usama Arif Acked-by: David Hildenbrand Acked-by: Johannes Weiner Acked-by: Roman Gushchin --- v1 -> v2: - Collected acks - Added cc for stable@vger.kernel.org and link of initial report (Johannes) --- include/linux/page-flags.h | 12 ++---------- mm/huge_memory.c | 8 ++++---- 2 files changed, 6 insertions(+), 14 deletions(-) diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h index cf46ac720802..691506bdf2c5 100644 --- a/include/linux/page-flags.h +++ b/include/linux/page-flags.h @@ -862,18 +862,10 @@ static inline void ClearPageCompound(struct page *pag= e) ClearPageHead(page); } FOLIO_FLAG(large_rmappable, FOLIO_SECOND_PAGE) -FOLIO_TEST_FLAG(partially_mapped, FOLIO_SECOND_PAGE) -/* - * PG_partially_mapped is protected by deferred_split split_queue_lock, - * so its safe to use non-atomic set/clear. - */ -__FOLIO_SET_FLAG(partially_mapped, FOLIO_SECOND_PAGE) -__FOLIO_CLEAR_FLAG(partially_mapped, FOLIO_SECOND_PAGE) +FOLIO_FLAG(partially_mapped, FOLIO_SECOND_PAGE) #else FOLIO_FLAG_FALSE(large_rmappable) -FOLIO_TEST_FLAG_FALSE(partially_mapped) -__FOLIO_SET_FLAG_NOOP(partially_mapped) -__FOLIO_CLEAR_FLAG_NOOP(partially_mapped) +FOLIO_FLAG_FALSE(partially_mapped) #endif =20 #define PG_head_mask ((1UL << PG_head)) diff --git a/mm/huge_memory.c b/mm/huge_memory.c index 2da5520bfe24..120cd2cdc614 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -3583,7 +3583,7 @@ int split_huge_page_to_list_to_order(struct page *pag= e, struct list_head *list, !list_empty(&folio->_deferred_list)) { ds_queue->split_queue_len--; if (folio_test_partially_mapped(folio)) { - __folio_clear_partially_mapped(folio); + folio_clear_partially_mapped(folio); mod_mthp_stat(folio_order(folio), MTHP_STAT_NR_ANON_PARTIALLY_MAPPED, -1); } @@ -3695,7 +3695,7 @@ bool __folio_unqueue_deferred_split(struct folio *fol= io) if (!list_empty(&folio->_deferred_list)) { ds_queue->split_queue_len--; if (folio_test_partially_mapped(folio)) { - __folio_clear_partially_mapped(folio); + folio_clear_partially_mapped(folio); mod_mthp_stat(folio_order(folio), MTHP_STAT_NR_ANON_PARTIALLY_MAPPED, -1); } @@ -3739,7 +3739,7 @@ void deferred_split_folio(struct folio *folio, bool p= artially_mapped) spin_lock_irqsave(&ds_queue->split_queue_lock, flags); if (partially_mapped) { if (!folio_test_partially_mapped(folio)) { - __folio_set_partially_mapped(folio); + folio_set_partially_mapped(folio); if (folio_test_pmd_mappable(folio)) count_vm_event(THP_DEFERRED_SPLIT_PAGE); count_mthp_stat(folio_order(folio), MTHP_STAT_SPLIT_DEFERRED); @@ -3832,7 +3832,7 @@ static unsigned long deferred_split_scan(struct shrin= ker *shrink, } else { /* We lost race with folio_put() */ if (folio_test_partially_mapped(folio)) { - __folio_clear_partially_mapped(folio); + folio_clear_partially_mapped(folio); mod_mthp_stat(folio_order(folio), MTHP_STAT_NR_ANON_PARTIALLY_MAPPED, -1); } --=20 2.43.5