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[2620:137:e000::1:20]) by mx.google.com with ESMTP id u15-20020a63470f000000b0051b280be4a2si4920265pga.486.2023.04.14.11.09.52; Fri, 14 Apr 2023 11:10:11 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20; Authentication-Results: mx.google.com; dkim=pass header.i=@google.com header.s=20221208 header.b=g9SpJgAT; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=REJECT sp=REJECT dis=NONE) header.from=google.com Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229930AbjDNRyw (ORCPT + 99 others); Fri, 14 Apr 2023 13:54:52 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42820 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229564AbjDNRyu (ORCPT ); Fri, 14 Apr 2023 13:54:50 -0400 Received: from mail-yw1-x1149.google.com (mail-yw1-x1149.google.com [IPv6:2607:f8b0:4864:20::1149]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 30F29210C for ; Fri, 14 Apr 2023 10:54:49 -0700 (PDT) Received: by mail-yw1-x1149.google.com with SMTP id 00721157ae682-54fbb2ee579so64040757b3.14 for ; Fri, 14 Apr 2023 10:54:49 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20221208; t=1681494888; x=1684086888; h=cc:to:from:subject:message-id:mime-version:date:from:to:cc:subject :date:message-id:reply-to; bh=sxtuJlZyuhJWBSe3BUp1o+R468Jyg7wjt5EQDKL8liw=; b=g9SpJgATsQDIYrkaPJd8d+PpBLT6jxYfne0OaHPIARm2IOQH+5ZUzrk668RVIdTFIK sxOkrjHFb2IwJhV+Rhhqr+Ms2OhPNi3AodJ+9OY+2GG2/dSng1wTYMa57UFr7FfZAVxI Mjh/iCg/xVEVvZMZlFypxHv6CoV31SltYbDHcAJCNrxBVXuHnfWdWgPZy7WTw1rRq2XX TXhZzJwJ3E/Ie4KgOXvM9CGQPa5RcER+MZF/7gxO1S4H4wu9t0bNr4IGAKdJ6Cqg7aGH BaxrJvra46EdXACNO7xHjaZO0BZXtOmHgL+PMxZE4/oVvLRUiP56FT8IvxbimldOWzpD U8NA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1681494888; x=1684086888; h=cc:to:from:subject:message-id:mime-version:date:x-gm-message-state :from:to:cc:subject:date:message-id:reply-to; bh=sxtuJlZyuhJWBSe3BUp1o+R468Jyg7wjt5EQDKL8liw=; b=a6PAdwh6iKzhaUGvdJsmCMnvJvv/F/B4ciY0hKXWen3QRQ0MOECxeQ172NLcNIDDAs NuzYSEJxazm2q/YRkSDoiQ0ivwd57TgBcLVRO/BK/EKeTUfdY3aAjx1gH3IgLx4+/c1P ZFhyLrdX/hC3bGmMdfil+0ObFBcNNKcZJ3bW0nRjVD5yZNgcIQAHs1aXEQuRY/1xh7O7 NOVQEc7CSsmBB03+xiCzGlI1TE1J2VxdnQ1lV+dOd9QGOsG1JZbMVHgyOLrz+u03ZN+y C0wEEahKDxYpooSpnfBORTwuwS9JO55VcfQkrhRo3NOjoux1ztn9aBBdiX5fNINQkORb EkcA== X-Gm-Message-State: AAQBX9dQlPl7cbO5uFUM1P5bfN7yydTx0UFza1M4Mpk6a91EIQSo+gQY 7J0Us05wy0npzhm59IQuXvi0UmzC8dk= X-Received: from surenb-desktop.mtv.corp.google.com ([2620:15c:211:201:46c0:7584:f020:e09f]) (user=surenb job=sendgmr) by 2002:a25:730c:0:b0:b91:b64e:743d with SMTP id o12-20020a25730c000000b00b91b64e743dmr1199758ybc.9.1681494888506; Fri, 14 Apr 2023 10:54:48 -0700 (PDT) Date: Fri, 14 Apr 2023 10:54:44 -0700 Mime-Version: 1.0 X-Mailer: git-send-email 2.40.0.634.g4ca3ef3211-goog Message-ID: <20230414175444.1837474-1-surenb@google.com> Subject: [PATCH 1/1] mm: do not increment pgfault stats when page fault handler retries From: Suren Baghdasaryan To: akpm@linux-foundation.org Cc: willy@infradead.org, hannes@cmpxchg.org, mhocko@suse.com, josef@toxicpanda.com, jack@suse.cz, ldufour@linux.ibm.com, laurent.dufour@fr.ibm.com, michel@lespinasse.org, liam.howlett@oracle.com, jglisse@google.com, vbabka@suse.cz, minchan@google.com, dave@stgolabs.net, punit.agrawal@bytedance.com, lstoakes@gmail.com, surenb@google.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, kernel-team@android.com X-Spam-Status: No, score=-9.6 required=5.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,RCVD_IN_DNSWL_NONE, SPF_HELO_NONE,SPF_PASS,T_SCC_BODY_TEXT_LINE,USER_IN_DEF_DKIM_WL autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org X-getmail-retrieved-from-mailbox: =?utf-8?q?INBOX?= X-GMAIL-THRID: =?utf-8?q?1763176152008191411?= X-GMAIL-MSGID: =?utf-8?q?1763176152008191411?= If the page fault handler requests a retry, we will count the fault multiple times. This is a relatively harmless problem as the retry paths are not often requested, and the only user-visible problem is that the fault counter will be slightly higher than it should be. Nevertheless, userspace only took one fault, and should not see the fact that the kernel had to retry the fault multiple times. Fixes: 6b4c9f446981 ("filemap: drop the mmap_sem for all blocking operations") Signed-off-by: Suren Baghdasaryan Reviewed-by: Matthew Wilcox (Oracle) --- Patch applies cleanly over linux-next and mm-unstable mm/memory.c | 16 ++++++++++------ 1 file changed, 10 insertions(+), 6 deletions(-) diff --git a/mm/memory.c b/mm/memory.c index 1c5b231fe6e3..d88f370eacd1 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -5212,17 +5212,16 @@ vm_fault_t handle_mm_fault(struct vm_area_struct *vma, unsigned long address, __set_current_state(TASK_RUNNING); - count_vm_event(PGFAULT); - count_memcg_event_mm(vma->vm_mm, PGFAULT); - ret = sanitize_fault_flags(vma, &flags); if (ret) - return ret; + goto out; if (!arch_vma_access_permitted(vma, flags & FAULT_FLAG_WRITE, flags & FAULT_FLAG_INSTRUCTION, - flags & FAULT_FLAG_REMOTE)) - return VM_FAULT_SIGSEGV; + flags & FAULT_FLAG_REMOTE)) { + ret = VM_FAULT_SIGSEGV; + goto out; + } /* * Enable the memcg OOM handling for faults triggered in user @@ -5253,6 +5252,11 @@ vm_fault_t handle_mm_fault(struct vm_area_struct *vma, unsigned long address, } mm_account_fault(regs, address, flags, ret); +out: + if (!(ret & VM_FAULT_RETRY)) { + count_vm_event(PGFAULT); + count_memcg_event_mm(vma->vm_mm, PGFAULT); + } return ret; }