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X-IronPort-AV: E=McAfee;i="6600,9927,10819"; a="379031041" X-IronPort-AV: E=Sophos;i="6.02,220,1688454000"; d="scan'208";a="379031041" Received: from fmsmga005.fm.intel.com ([10.253.24.32]) by orsmga102.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 01 Sep 2023 14:06:07 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=McAfee;i="6600,9927,10819"; a="1070871974" X-IronPort-AV: E=Sophos;i="6.02,220,1688454000"; d="scan'208";a="1070871974" Received: from jroorda-mobl4.ger.corp.intel.com (HELO box.shutemov.name) ([10.252.32.118]) by fmsmga005-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 01 Sep 2023 14:05:58 -0700 Received: by box.shutemov.name (Postfix, from userid 1000) id 94702104994; Sat, 2 Sep 2023 00:05:55 +0300 (+03) Date: Sat, 2 Sep 2023 00:05:55 +0300 From: kirill.shutemov@linux.intel.com To: Vlastimil Babka Cc: seanjc@google.com, ackerleytng@google.com, akpm@linux-foundation.org, anup@brainfault.org, aou@eecs.berkeley.edu, chao.p.peng@linux.intel.com, chenhuacai@kernel.org, david@redhat.com, isaku.yamahata@gmail.com, jarkko@kernel.org, jmorris@namei.org, kvm-riscv@lists.infradead.org, kvm@vger.kernel.org, kvmarm@lists.linux.dev, liam.merwick@oracle.com, linux-arm-kernel@lists.infradead.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mips@vger.kernel.org, linux-mm@kvack.org, linux-riscv@lists.infradead.org, linux-security-module@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, mail@maciej.szmigiero.name, maz@kernel.org, michael.roth@amd.com, mpe@ellerman.id.au, oliver.upton@linux.dev, palmer@dabbelt.com, paul.walmsley@sifive.com, paul@paul-moore.com, pbonzini@redhat.com, qperret@google.com, serge@hallyn.com, tabba@google.com, vannapurve@google.com, wei.w.wang@intel.com, willy@infradead.org, yu.c.zhang@linux.intel.com Subject: Re: [PATCH gmem FIXUP] mm, compaction: make testing mapping_unmovable() safe Message-ID: <20230901210555.j5d5a4azmkxzlnn2@box.shutemov.name> References: <20230901082025.20548-2-vbabka@suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20230901082025.20548-2-vbabka@suse.cz> X-Rspamd-Queue-Id: 595B8120023 X-Rspam-User: X-Rspamd-Server: rspam02 X-Stat-Signature: tmy3w1ff9jy5whj5cd9hhumgpzeco9tz X-HE-Tag: 1693602369-36498 X-HE-Meta: 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 6h0BPY1i Dqk66hrnQwm75CPqNEs99v3wZqu4HyBm0AhXV5Xcf5p7/UHu/K+ojCXSLczFgaRGbhZr4sQYTjzSrTS2hYjSB536yaOHQA0wvQ0WHHE32sST1DkNN7a3f+LPpKSi6iB/n0yB6Bax8IRBSUROwg2MkuVPxtatb9CB5J9FSvuQc332lAETrpxaZK7fYPnvhaiC1XQLO/+VvsrQ8Uh8lrNQyijBDf9Kvc9CkWBqSDnW/jtnI94Q= 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, Sep 01, 2023 at 10:20:26AM +0200, Vlastimil Babka wrote: > As Kirill pointed out, mapping can be removed under us due to > truncation. Test it under folio lock as already done for the async > compaction / dirty folio case. To prevent locking every folio with > mapping to do the test, do it only for unevictable folios, as we can > expect the unmovable mapping folios are also unevictable - it is the > case for guest memfd folios. > > Also incorporate comment update suggested by Matthew. > > Fixes: 3424873596ce ("mm: Add AS_UNMOVABLE to mark mapping as completely unmovable") > Signed-off-by: Vlastimil Babka Superficially looks good to me. But I don't really understand this code path to Ack. -- Kiryl Shutsemau / Kirill A. Shutemov