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Tue, 6 Sep 2022 14:43:33 GMT Received: from b06wcsmtp001.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id C67E4A4060; Tue, 6 Sep 2022 14:43:33 +0000 (GMT) Received: from b06wcsmtp001.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id A0FCDA4054; Tue, 6 Sep 2022 14:43:32 +0000 (GMT) Received: from [9.101.4.33] (unknown [9.101.4.33]) by b06wcsmtp001.portsmouth.uk.ibm.com (Postfix) with ESMTP; Tue, 6 Sep 2022 14:43:32 +0000 (GMT) Message-ID: Date: Tue, 6 Sep 2022 16:43:32 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:102.0) Gecko/20100101 Thunderbird/102.2.0 Subject: Re: [RFC PATCH RESEND 08/28] mm/khugepaged: mark VMA as locked while collapsing a hugepage Content-Language: fr To: Suren Baghdasaryan , akpm@linux-foundation.org Cc: michel@lespinasse.org, jglisse@google.com, mhocko@suse.com, vbabka@suse.cz, hannes@cmpxchg.org, mgorman@suse.de, dave@stgolabs.net, willy@infradead.org, liam.howlett@oracle.com, peterz@infradead.org, laurent.dufour@fr.ibm.com, paulmck@kernel.org, luto@kernel.org, songliubraving@fb.com, peterx@redhat.com, david@redhat.com, dhowells@redhat.com, hughd@google.com, bigeasy@linutronix.de, kent.overstreet@linux.dev, rientjes@google.com, axelrasmussen@google.com, joelaf@google.com, minchan@google.com, kernel-team@android.com, linux-mm@kvack.org, linux-arm-kernel@lists.infradead.org, linuxppc-dev@lists.ozlabs.org, x86@kernel.org, linux-kernel@vger.kernel.org References: <20220901173516.702122-1-surenb@google.com> <20220901173516.702122-9-surenb@google.com> From: Laurent Dufour In-Reply-To: <20220901173516.702122-9-surenb@google.com> Content-Type: text/plain; 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dmarc=pass (policy=none) header.from=ibm.com X-Rspam-User: X-Rspamd-Server: rspam12 X-Stat-Signature: au3z4ur5cqeca1hnbafge87s6mj4hxd3 X-HE-Tag: 1662475437-21093 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: Le 01/09/2022 à 19:34, Suren Baghdasaryan a écrit : > Protect VMA from concurrent page fault handler while modifying it in > collapse_huge_page. Is the goal to protect changes in the anon_vma structure? AFAICS, the vma it self is not impacted here, only the anon_vma and the PMD/PTE are touched, and they have their own protection mechanism, isn't it? > > Signed-off-by: Suren Baghdasaryan > --- > mm/khugepaged.c | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/mm/khugepaged.c b/mm/khugepaged.c > index 01f71786d530..030680633989 100644 > --- a/mm/khugepaged.c > +++ b/mm/khugepaged.c > @@ -1072,6 +1072,7 @@ static void collapse_huge_page(struct mm_struct *mm, > if (mm_find_pmd(mm, address) != pmd) > goto out_up_write; > > + vma_mark_locked(vma); > anon_vma_lock_write(vma->anon_vma); > > mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, NULL, mm,