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[24.6.216.183]) by smtp.gmail.com with ESMTPSA id t17-20020a170902e1d100b0016d8b0dfd61sm1179202pla.178.2022.08.04.10.16.52 (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Thu, 04 Aug 2022 10:16:53 -0700 (PDT) Content-Type: text/plain; charset=us-ascii Mime-Version: 1.0 (Mac OS X Mail 16.0 \(3696.120.41.1.1\)) Subject: Re: [PATCH 2/2] mm: Remember young bit for page migrations From: Nadav Amit In-Reply-To: Date: Thu, 4 Aug 2022 10:16:50 -0700 Cc: LKML , Linux MM , Andrea Arcangeli , Andi Kleen , Andrew Morton , Hugh Dickins , Huang Ying , "Kirill A . Shutemov" , Vlastimil Babka , David Hildenbrand , Minchan Kim Content-Transfer-Encoding: 7bit Message-Id: <40FDA6B1-EB53-484D-91A0-323606199C4E@gmail.com> References: <20220803012159.36551-1-peterx@redhat.com> <20220803012159.36551-3-peterx@redhat.com> To: Peter Xu X-Mailer: Apple Mail (2.3696.120.41.1.1) ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1659633415; a=rsa-sha256; cv=none; b=f8CsQ//ww8pjutJ9rYRcAJvqB/9UHrExs+bjhmc2nn3Hb1G9rDQCpbPVbgsvpHdQh7oAP9 5HCr2rxsJ5h7nrEkhXPuqrZQ8kdpJkEl42j1ZBaBPcxERqFnjbx4YKZgNNUyJJxZyugkmh Q/6n/Pi3vtCUysyFUwfzcV7IFVqOipI= ARC-Authentication-Results: i=1; imf28.hostedemail.com; dkim=pass header.d=gmail.com header.s=20210112 header.b=VqJbMd6U; dmarc=pass (policy=none) header.from=gmail.com; spf=pass (imf28.hostedemail.com: domain of nadav.amit@gmail.com designates 209.85.216.49 as permitted sender) smtp.mailfrom=nadav.amit@gmail.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1659633415; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=QHDKoLkk6GDmpCFPVivtCs2hgFz4v8Al+bShpzHhVfw=; b=zYjFiyxEkTq+4or4yfKY4Wel0t5IfCdNwZno8ZDiK3SVtZuDzO45qzc7uv8oINEbAOtNSI 8gW5h9bLps/rKG7bd5Y+lJsn1sFHRd6mCMdF8vUGdqeANQfCpq3QgPUbc4CVeyZ1ya4lHz hTe5Klzo4d7ScPAAqV0PKVA+FmqB+k4= X-Stat-Signature: 5csrx1dzsn1twznzbkk7r34i38uypini X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: 7A354C0117 Authentication-Results: imf28.hostedemail.com; dkim=pass header.d=gmail.com header.s=20210112 header.b=VqJbMd6U; dmarc=pass (policy=none) header.from=gmail.com; spf=pass (imf28.hostedemail.com: domain of nadav.amit@gmail.com designates 209.85.216.49 as permitted sender) smtp.mailfrom=nadav.amit@gmail.com X-Rspam-User: X-HE-Tag: 1659633415-774962 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 Aug 4, 2022, at 10:07 AM, Peter Xu wrote: > On Wed, Aug 03, 2022 at 11:42:39PM -0700, Nadav Amit wrote: >> On Aug 3, 2022, at 9:45 AM, Peter Xu wrote: > > For this series, I can think more of dropping the young bit for migration > entry during these madvises (which should be relatively safe with the > pgtable held, since I don't need to touch the page but just modify the swap > entry within), but probably that's not really the major problem here, so > not sure whether that matters a huge lot (e.g., for FREE we should really > drop the whole entry?). Sounds good to me. I just had a look whether the swap entry should be checked and hit these additional cases, so I thought they are worthy of consideration. But as they are already not handling some cases, which is valid for madvise's hints, leaving it to later sounds fine. Handling migration entries anyhow might not be worthy of the risk of breaking something.