From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=95.215.58.244 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1793018156; b=3NDa127Tcn3yiC6fAig/7vA6Gp6vXWaZs9p4QvK+tPvQcD+BKKafh2hBTMV9qxNrJc1z xv7/N4XJJvaZYCgSC2aiWk22HWefHpwmYJzNKS6PlEMRwLvmwCPuWVwbQMDh0O3ueQWKQ O9iQ9m7Tsgh+eRyECDZcnllkv5K0rz4bjWHr+aaJJmS3PvHmjDWVwGrnHHqZ86JS2Fa98 8dirAKg7xLmjy7UCEVdhIkUpIStpY+TmN2Q205CLpzwn1+1qaZgC5mJ44z+fBHYDzkv9e nx08YzzmxgxC4h/K2Us/PvNdSC4bVLEuTZPCwbhD1VQr4FSBIVhFnSDIBXCS8/OUQNg== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793018156; 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=M7EefUh3aqRq+/kXeTZJUHXPcDw8CBwlgMa4LUajmOY=; b=5Pbj/X/4A4l8atiROR15QOHCMKtp9ayFJvEtT9ER5jl4Ny01jBR/egDWecKaLwa0m209 IKZ+l0zLXgOMhC6LQ4087W8BjWRbCtwgJTtKEGLMoxm2+rxfGO8g+fKIEcaGLvHt9Drqt 3r1UKiSmHodUiJFMpDniWIpWcBq00BuUwMZwfHJ0nfV/8fEuqVU5CZh5t62jT6VRssaIu k2/1OknGW7vcUmDS0/f7s2LWwP3Zwt0AHfcE+aabrlVvha2gTpszNHqyGj+/5S0UDgKr1 42C2h702HGAO0V4DYKuxbI1k4KYoq10bvmNE2FyOmUqVQgkQs5/uznGsm6V29jrRLQQ== 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=QDYnBlVj; arc=none smtp.remote-ip=95.215.58.244 Received: from mta1.migadu.com (out-244.mta1.migadu.com [95.215.58.244]) (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 0842E606A31A for ; Mon, 26 Oct 2026 12:35:55 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.2 smtp.subspace.kernel.org 0842E606A31A 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=QDYnBlVj X-Envelope-To: linux-kernel@vger.kernel.org DKIM-Signature: a=rsa-sha256; bh=P4HvR1T1qWQJ8zvWY6aCuA2NNhAyIJqSmu7qznxYcdI=; c=simple/simple; d=linux.dev; h=from:to:subject:date:message-id:mime-version:content-type; s=key1; t=1793018154; v=1; x=1793622954; b=QDYnBlVjApUfVb32w5CMpG6fcutS3RlXBpwWR9XiQXVZUC+e7uI7/TcWUVsYf+tY3g0+6vM/ ypyeq8TSPTvWOkU4fkRnEiyoq9E0lNqt8nlfltcBIHKN61C4wkdWp0sjHeXj5rTvqds0iAJd2ID 4nUIefE0ECKycUHjLyRD1cyY= X-Envelope-To: linux-kernel@vger.kernel.org Received: by smtp.migadu.com with ESMTPS id 7e1874fcba217f36; Mon, 26 Oct 2026 12:35:53 +0000 X-Mizu-Trace-ID: 7e1874fcba217f36 X-Migadu-Flow: FLOW_OUT Message-ID: <67e0c2ce-c763-4705-a965-1ca84898e438@linux.dev> Date: Mon, 26 Oct 2026 20:35:39 +0800 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 v3 1/1] khugepaged: fix readahead lock inversion in collapse_file() To: "David Hildenbrand (Arm)" , Baolin Wang Cc: akpm@linux-foundation.org, ziy@nvidia.com, liam@infradead.org, nico.pache@linux.dev, ryan.roberts@arm.com, dev.jain@arm.com, baohua@kernel.org, usama.arif@linux.dev, kas@kernel.org, jack@suse.cz, djwong@kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, hch@lst.de, syzbot+16bf7cd0ebeb1de93aa5@syzkaller.appspotmail.com, ngocthang2710.1999@gmail.com, willy@infradead.org, rppt@kernel.org, ljs@kernel.org, Pedro Falcato References: <20261016065920.4153-1-lance.yang@linux.dev> <27e5aadc-2d68-428f-a958-308e4a75c058@linux.alibaba.com> <6a005d89-df5b-4524-a4b9-c637cb15f1ee@linux.alibaba.com> <3be96a1c-7cfb-4cd0-a4fb-16209494d041@kernel.org> Content-Language: en-US From: Lance Yang In-Reply-To: <3be96a1c-7cfb-4cd0-a4fb-16209494d041@kernel.org> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 2026/10/26 19:26, David Hildenbrand (Arm) wrote: > On 10/18/26 04:47, Baolin Wang wrote: >> >> >> On 10/17/26 3:41 PM, Lance Yang wrote: >>> >>> >>> On 2026/10/17 13:43, Baolin Wang wrote: >>>> >>>> >>>> >>>> OK. >>>> >>>> >>>> Sounds good. >>>> >>>> >>>> But why not add RA logic in collapse_pmd(), as we do for >>>> SCAN_PAGE_DIRTY_OR_WRITEBACK? There's already retry logic there, and this >>>> would also simplify the long collapse_file(). >>> >>> That would be cleaner, yeah. Some older stable trees don't have that >>> outer retry loop, though ... I'd prefer to get the fix backported first, >>> then move the RA/retry logic out in a follow-up, wdyt? >> >> IIRC, the approach to bug fixes is to fix bugs properly and cleanly for >> upstream, without being constrained by backporting requirements. >> >> Anyway, I don't have a strong opinion on this. Let's also see what David prefers. > > Let's get this fixed in a acceptable way in a reasonable timeframe; it's been > broken for too long. ... and follow up with bigger cleanups later. > > @Lance is this version good to review for that purpose or are you planning a resend? Right, as for the bigger cleanup, that can come later. Will resend the current version as-is :)