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Received: from willy by casper.infradead.org with local (Exim 4.94.2 #2 (Red Hat Linux)) id 1poScf-00BXC2-Vu; Mon, 17 Apr 2023 17:26:38 +0000 Date: Mon, 17 Apr 2023 18:26:37 +0100 From: Matthew Wilcox To: Suren Baghdasaryan Cc: akpm@linux-foundation.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, linux-mm@kvack.org, linux-kernel@vger.kernel.org, kernel-team@android.com Subject: Re: [PATCH v2 1/1] mm: do not increment pgfault stats when page fault handler retries Message-ID: References: <20230415000818.1955007-1-surenb@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20230415000818.1955007-1-surenb@google.com> X-Rspam-User: X-Rspamd-Server: rspam03 X-Stat-Signature: ahbnqqufp9rzkipypw6seqpb3fi9qjb8 X-Rspamd-Queue-Id: DA6AC40021 X-HE-Tag: 1681752424-930122 X-HE-Meta: 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 qHuJD6zq rLUUrkXZzhzA8VDlG6kNpDRmPDmz3A6DfTbzMg93BZWCWLEeirCyWWNRaDJDGzT6JTgtnx5t2KERx7CgE6MRrkOJVfXHYogx9yAZsDnNVVTtYwprvEovBkPBYcf8lwt97vNpmMtEDESPSEdpDq+gDPFpH4PM0Mkcaes/5 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Fri, Apr 14, 2023 at 05:08:18PM -0700, Suren Baghdasaryan wrote: > /* > - * We don't do accounting for some specific faults: > - * > - * - Unsuccessful faults (e.g. when the address wasn't valid). That > - * includes arch_vma_access_permitted() failing before reaching here. > - * So this is not a "this many hardware page faults" counter. We > - * should use the hw profiling for that. > - * > - * - Incomplete faults (VM_FAULT_RETRY). They will only be counted > - * once they're completed. > + * Do not account for incomplete faults (VM_FAULT_RETRY). They will be I don't think you need the "(VM_FAULT_RETRY)" here. > @@ -5180,21 +5186,22 @@ static vm_fault_t sanitize_fault_flags(struct vm_area_struct *vma, > vm_fault_t handle_mm_fault(struct vm_area_struct *vma, unsigned long address, > unsigned int flags, struct pt_regs *regs) > { > + /* Copy vma->vm_mm in case mmap_lock is dropped and vma becomes unstable. */ How about: /* If the fault handler drops the mmap_lock, vma may be freed */ > + struct mm_struct *mm = vma->vm_mm;