From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=95.215.58.235 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1792964931; b=hglu9f/o4dGMkJX0Bp2j3HAXTdPobmy8lTPyU1aR2YoHIY5d2BEFO/+Yf4hkQzUrcjTf YRAUhDK7799xK/O4MMflwZwnC+oLjMRlu1zqjxW/m8vijooE73Mi70K50x+X7ewatZED0 bYnrq/DmvdrC+brBpK/kEduU61YhWVL9l0tx8OxolR53Iv7n3Mltv7jNI1J9y35f5gA5p I6KOMMof6+uMecg39clDtJBrHJMgTgBKLn+ew/AWj3igfjnE3DmiAU9yzsvCSK9Kjo6V8 2wPdieDJmpRfPKu0klTKu0AkTa83XdSl8xxQT6NkndRi+qaTs4Ra62/7kTghy9JeVEw== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1792964931; h=DMARC-Filter:X-Envelope-To:DKIM-Signature:X-Envelope-To:Received: X-Mizu-Trace-ID:X-Migadu-Flow:Message-ID:Date:MIME-Version:User-Agent: Subject:To:Cc:References:Content-Language:From:In-Reply-To: Content-Type:Content-Transfer-Encoding; bh=7wQNgAvrV53M6g73xXbn+Hsa5Wpgb9uHDA2CEi88MY8=; b=DFh9jW6FoCDqYgP4pSSWGSmq7HZ6Bxv6ohCZeRM0YqOJm9WxGUSGL97Usy2fafU4aLz3 Sl25J7u716GwQ88/AFiBJYUO5dIH8u7lpd/+5PUnDHM9yU5XeWueqH33sc3/hh3czRttu n2CUywNa3A0BFps6Apal2VBDqkAcNRH9ue30asZcGrVEIoiwNKQO/tD7nlh9XegDbExdo k6qbLcH8H4b1WvuJSRN5BAlX84ygTvVCTUL/Wd8OJHYCyNUfumf5XiQvKrY+UqRgggTvN /3ZOcB19kexCz1A5UVYpcvL8XRADQEvzHJ7LnbIyHiON10wM+f3bs7SQtVJW1SvY6Fg== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass header.d=linux.dev header.i=@linux.dev header.a=rsa-sha256 header.s=key1 header.b=gWkUhUFU; arc=none smtp.remote-ip=95.215.58.235 Received: from mta1.migadu.com (out-235.mta1.migadu.com [95.215.58.235]) (using TLSv1.3 with cipher TLS_AES_128_GCM_SHA256 (128/128 bits) key-exchange X25519 server-signature ECDSA (prime256v1) server-digest SHA256) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 2CAF1606A31A for ; Sun, 25 Oct 2026 21:48:49 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.2 smtp.subspace.kernel.org 2CAF1606A31A Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key, unprotected) header.d=linux.dev header.i=@linux.dev header.a=rsa-sha256 header.s=key1 header.b=gWkUhUFU X-Envelope-To: linux-kernel@vger.kernel.org DKIM-Signature: a=rsa-sha256; bh=FW93I9g2tFhlVSvMbZvJhIsiJI9bo4PZOSNREMcmxDA=; c=simple/simple; d=linux.dev; h=from:to:subject:date:message-id:mime-version:content-type; s=key1; t=1792964928; v=1; x=1793569728; b=gWkUhUFUyP2n9w1XqfxuzV06+ZqN3YN+wNJCYBrB4HxP5Nwf4YoA/Ifr7LPlYyKV633fnYzN ZQA0k94WlZsm0a64RNpARKHYrHVnMTF+ivYvmRNLgLaeOBang+tBO6hINmNWwGhQVq7MrwtftlD 8ilzZwtbnrH9kXJ2kDI26e2M= X-Envelope-To: linux-kernel@vger.kernel.org Received: by smtp.migadu.com with ESMTPS id e5eed0b9c945e22a; Sun, 25 Oct 2026 21:48:48 +0000 X-Mizu-Trace-ID: e5eed0b9c945e22a X-Migadu-Flow: FLOW_OUT Message-ID: Date: Sun, 25 Oct 2026 15:48:43 -0600 X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 1/2] mm/huge_memory.c: skip zero-page remapping when underused THP shrinker is disabled To: Barry Song Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Andrew Morton , David Hildenbrand , Zi Yan , Baolin Wang , "Liam R. Howlett" , Ryan Roberts , Dev Jain , Lance Yang , Usama Arif , Kiryl Shutsemau , Yu Zhao , Xu Xin , Chengming Zhou , Matthew Brost , Joshua Hahn , Byungchul Park , Gregory Price , Ying Huang , Alistair Popple , Usama Arif , aarcange@redhat.com References: <20261025-b4-ksm_fixv2-v2-0-8b61ad0491f1@linux.dev> <20261025-b4-ksm_fixv2-v2-1-8b61ad0491f1@linux.dev> Content-Language: en-US From: Nico Pache In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit On 10/25/26 2:28 PM, Barry Song wrote: > On Mon, Oct 26, 2026 at 1:40 AM Nico Pache (Red Hat) > wrote: >> >> The zero-page remapping in __folio_split() was added to support the >> underused THP shrinker. When the shrinker is disabled via >> shrink_underused, gate TTU_USE_SHARED_ZEROPAGE on split_underused_thp >> to avoid scanning subpages for zero content unnecessarily. >> >> Suggested-by: David Hildenbrand >> Fixes: b1f202060afe ("mm: remap unused subpages to shared zeropage when splitting isolated thp") >> Signed-off-by: Nico Pache > > is b1f202060afe a correct fixes tag? as > commit b1f202060afe has no even "split_underused_thp" there. I believe so. IIUC these two series were merged together. While 81d3ff3c6f7 introduces the toggle, b1f202060afe is where the behavior started. I guess you could argue that the Fixes should include both? Not entirely sure! -- Nico > > it was introduced by 81d3ff3c6f7 ("mm: add sysfs entry to disable > splitting underused THPs").