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(p200300cbc7079d00930390ce6dcb2bc9.dip0.t-ipconnect.de. [2003:cb:c707:9d00:9303:90ce:6dcb:2bc9]) by smtp.gmail.com with ESMTPSA id c3-20020a1c3503000000b003dc0b0e1e47sm2405844wma.48.2023.01.24.02.19.03 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 24 Jan 2023 02:19:04 -0800 (PST) Message-ID: <4cb68043-1c06-6589-b83e-74847a06f457@redhat.com> Date: Tue, 24 Jan 2023 11:19:02 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.6.0 Subject: Re: [PATCH] mm/khugepaged: Fix ->anon_vma race To: "Kirill A. Shutemov" , g@box.shutemov.name Cc: Jann Horn , Andrew Morton , linux-mm@kvack.org, "Kirill A. Shutemov" , Zach O'Keefe , linux-kernel@vger.kernel.org, Yang Shi References: <20230111133351.807024-1-jannh@google.com> <20230112085649.gvriasb2t5xwmxkm@box.shutemov.name> <20230115190654.mehtlyz2rxtg34sl@box.shutemov.name> <20230116123403.fiyv22esqgh7bzp3@box.shutemov.name> <5a7fdfa7-5b25-0ed4-2479-661d387b397b@redhat.com> <20230116134710.n4dgtrutt6rqif62@box.shutemov.name> <1b8696ec-e2be-7b7b-705c-e2dcabb2e8e5@redhat.com> <20230124005102.ow33h7tfmj5eqyr3@box.shutemov.name> From: David Hildenbrand Organization: Red Hat In-Reply-To: <20230124005102.ow33h7tfmj5eqyr3@box.shutemov.name> X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Rspam-User: X-Rspamd-Server: rspam03 X-Stat-Signature: 5jqqmhynh33x3kgi36h7bwrsqfnh19b9 X-Rspamd-Queue-Id: F06DF40017 X-HE-Tag: 1674555547-487193 X-HE-Meta: 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 7x1hI1Wm RRwENvpqcl1oPFtgM5UiZbxidU3KuiE5977tUYjaA0iUev7h5FyQWFte3o7VdSHSSCBNokefRSOAeBoVIV7O+fc605M7d2IbOg3/FfS3UnUSJUorm880PnYW3EoCOXZPKdEiNSZ8TzIaGm03QJ0pp7BKrTLSLpdb6t/X6AOmiBlOqlPIrRA0cEmeRbnA+CjmfDSUvpj4Z9yjkYIAJLDx2MiWDYasVp7HMQZfTAAxuHws+UJziVS0H61p/ioUBzdidyHVH4MgKZ+qKvEOFS1E8Yw8KOBrekBjiA58ccMLjWWiu8WBR0N8ScJApLXDD0dBZh0rUsQNNBWZ9hKq3JWaQE1YtCIsc0oLOSZFaINSD/3KWQwPPR3vN12ipR4GFWnuSP/wANPlPHa6LztHn/Mnd1IlP6X25Z2re08Z/X+px/rI1XPOp+T4SKD1VOtEYZchbf3d2wveAB8IuRu8Jzj4SUsi8rA== 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 24.01.23 01:51, Kirill A. Shutemov wrote: > On Mon, Jan 23, 2023 at 12:07:05PM +0100, David Hildenbrand wrote: >>>> commit bedf03416913d88c796288f9dca109a53608c745 >>>> Author: Yang Shi >>>> Date: Wed Sep 7 11:01:44 2022 -0700 >>>> >>>> powerpc/64s/radix: don't need to broadcast IPI for radix pmd collapse flush >>>> The IPI broadcast is used to serialize against fast-GUP, but fast-GUP will >>>> move to use RCU instead of disabling local interrupts in fast-GUP. Using >>>> an IPI is the old-styled way of serializing against fast-GUP although it >>>> still works as expected now. >>>> And fast-GUP now fixed the potential race with THP collapse by checking >>>> whether PMD is changed or not. So IPI broadcast in radix pmd collapse >>>> flush is not necessary anymore. But it is still needed for hash TLB. >>> >>> Okay. But I think tlb_remove_table_sync_one() belongs inside >>> pmdp_collapse_flush(). Collapsing pmd table into huge page without >>> serialization is a bug. They should not be separate. >> >> Agreed. But I wonder if it should be moved into a generic >> pmdp_collapse_flush(), that calls an arch specific __pmdp_collapse_flush(). > > Um? There's no __pmdp_collapse_flush(). Did I imply that there is already one? ;) -- Thanks, David / dhildenb