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smtp.subspace.kernel.org; dkim=pass header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b="AbFmM/nq"; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 0455F606A32A for ; Mon, 26 Oct 2026 12:12:25 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key, unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=AbFmM/nq Received: by smtp.kernel.org (Postfix) with ESMTPSA id A6CFA1F031E3; Mon, 26 Oct 2026 12:12:19 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1793016745; bh=6qj8m8z1wbRyIk6+/HP994xBD+OWRY6Idbk7+z+pqbQ=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=AbFmM/nqEku80UT+Aw7V4iA4reTs6onG88eMdzcmBom8o9iffpHF/sioYmaT8MFxS LtxEjSXM4LrFlC9dmF1WxtG5wWM5ScaShfstE/EfTPFnEroTAzaqvaVB/nvIHa3+AH 4zDgcBgJtT+PVaa/K+cc2GU+45UEeNZmfpm9XFddPWcMaaxD0yOcaxDjMtqh2b4rkZ RJYozXPKbhWQCK5W3LEtL7Q4isI94VLRu+djE6ouv7LG3VcAcRDhr61UVV7ozu24bo i7U7SJrXOA+NSjKiHxDwQk6QodHCsJc1KAfo8LO/Kpw2Ya3dK0XfB/CrLALFZbMXy6 R3tK7qaGprDsg== Message-ID: <3be96a1c-7cfb-4cd0-a4fb-16209494d041@kernel.org> Date: Mon, 26 Oct 2026 12:26:39 +0100 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: Baolin Wang , Lance Yang , Pedro Falcato 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 References: <20261016065920.4153-1-lance.yang@linux.dev> <27e5aadc-2d68-428f-a958-308e4a75c058@linux.alibaba.com> <6a005d89-df5b-4524-a4b9-c637cb15f1ee@linux.alibaba.com> From: "David Hildenbrand (Arm)" Content-Language: en-US Autocrypt: addr=david@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 7bit 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? -- Cheers, David