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[91.12.103.101]) by smtp.gmail.com with ESMTPSA id s13sm1878592wmc.47.2021.11.23.09.26.09 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 23 Nov 2021 09:26:09 -0800 (PST) Message-ID: <1b400921-8bef-8073-10f9-a7cbb09cfefe@redhat.com> Date: Tue, 23 Nov 2021 18:26:08 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.2.0 Subject: Re: [PATCH] mm: split thp synchronously on MADV_DONTNEED To: Shakeel Butt Cc: "Kirill A . Shutemov" , Yang Shi , Zi Yan , Matthew Wilcox , Andrew Morton , linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <20211120201230.920082-1-shakeelb@google.com> <25b36a5c-5bbd-5423-0c67-05cd6c1432a7@redhat.com> <1b30d06d-f9c0-1737-13e6-2d1a7d7b8507@redhat.com> <92fe0c31-b083-28c4-d306-da8a3cd891a3@redhat.com> From: David Hildenbrand Organization: Red Hat In-Reply-To: X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: CF2CC900067C X-Stat-Signature: eewhsz4o1t5rrcdzb5j9ixfbst3ko197 Authentication-Results: imf29.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=GdX1AL33; dmarc=pass (policy=none) header.from=redhat.com; spf=none (imf29.hostedemail.com: domain of david@redhat.com has no SPF policy when checking 170.10.133.124) smtp.mailfrom=david@redhat.com X-HE-Tag: 1637688370-973884 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 23.11.21 18:24, Shakeel Butt wrote: > On Tue, Nov 23, 2021 at 9:20 AM David Hildenbrand wrote: >> >> On 23.11.21 18:17, Shakeel Butt wrote: >>> On Tue, Nov 23, 2021 at 8:57 AM David Hildenbrand wrote: >>>> >>> [...] >>>>>> >>>>>> I do wonder which these locking contexts are exactly, and if we could >>>>>> also do the same thing on ordinary munmap -- because I assume it can be >>>>>> similarly problematic for some applications. >>>>> >>>>> This is a good question regarding munmap. One main difference is >>>>> munmap takes mmap_lock in write mode and usually performance critical >>>>> applications avoid such operations. >>>> >>>> Maybe we can extend it too most page zapping, if that makes things simpler. >>>> >>> >>> Do you mean doing sync THP split for most of page zapping functions >>> (but only if that makes things simpler)? >>> >> >> Yes -- if there are no downsides. >> > > I will try. At the moment the assumption of "Not null zap_details > implies leave swap entries" is giving me a headache. Not only you, did you stumble over https://lkml.kernel.org/r/20211115134951.85286-1-peterx@redhat.com already? -- Thanks, David / dhildenb