From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out30-132.freemail.mail.aliyun.com (out30-132.freemail.mail.aliyun.com [115.124.30.132]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 701F2487BE for ; Wed, 7 Jan 2026 01:21:38 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=115.124.30.132 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1767748901; cv=none; b=kAIl5EW4XTrTNb7Xapi1gDdATcGTPxH2RfkCk6lcZ+2uaRI1Yh31q0M0J2RCSndRsjEbhQr2rCzuPh+zkjmRc+mCHWW84IFL+CMWVLBKfFspZcmIiyn6fYl7Bdpb4Pu20lqBkRjWcL0MGCSa5pr+CObRnn7WEXhQSBlyFrN5u3E= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1767748901; c=relaxed/simple; bh=R6yaVV62CQvcKjJHQDfCq5hgKwuyLY6UhhhAI3o/me8=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=NxDLuS0KMOrEOe/QyY8nF5H6lL270iLs0fA62+TKF50y9S2mXwe4nrHkrHLeW9ShtAv622A4s1fZcgMuWj+r2NsSOe67mc1wq9yr68K2gAQfrGHsWuIGbp8sd6S3dZpF1oWxqFURvd3TGKgvpT38j96eL8UF2H7ohrzCTVVm8/8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.alibaba.com; spf=pass smtp.mailfrom=linux.alibaba.com; dkim=pass (1024-bit key) header.d=linux.alibaba.com header.i=@linux.alibaba.com header.b=bqCYQ7A9; arc=none smtp.client-ip=115.124.30.132 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.alibaba.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.alibaba.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.alibaba.com header.i=@linux.alibaba.com header.b="bqCYQ7A9" DKIM-Signature:v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.alibaba.com; s=default; t=1767748890; h=Message-ID:Date:MIME-Version:Subject:To:From:Content-Type; bh=2zc4DIOdl1Pd7NU3lqgjLL5P97EqbXnp15c7Yi08/Rs=; b=bqCYQ7A9oTwQ/H1kx28XVskkqFjBZ7vEFfqz1Z8n0vrWpp4iipP+R7XxauRt6du5ooblsThXkBgP8n+IfNC37J3eyCFvEpjgAa8X9/7RgVNQTfYcu/q8HJCKxvVaFAj3ywRhANNH44n8lb6JaK2rnhoYMgFzTFrjbNNnOsz/KFc= Received: from 30.74.144.121(mailfrom:baolin.wang@linux.alibaba.com fp:SMTPD_---0WwWwVyP_1767748572 cluster:ay36) by smtp.aliyun-inc.com; Wed, 07 Jan 2026 09:16:12 +0800 Message-ID: <9c4b8d43-1c01-46f0-8e1e-435a19b8713b@linux.alibaba.com> Date: Wed, 7 Jan 2026 09:16:11 +0800 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] mm/shmem: fix uninitialized folio in shmem_symlink To: Matthew Wilcox Cc: Brian Foster , Barry Song <21cnbao@gmail.com>, akpm@linux-foundation.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Hugh Dickins , syzbot+178fff6149127421c2cc@syzkaller.appspotmail.com References: <20251224094027.65842-1-21cnbao@gmail.com> <2b12f63b-ceab-4d3e-a06f-f41e6b1b2d23@linux.alibaba.com> From: Baolin Wang In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit On 1/7/26 2:46 AM, Matthew Wilcox wrote: > On Tue, Jan 06, 2026 at 11:47:44AM +0800, Baolin Wang wrote: >> Why I prefer Barry's fix: First, the symlink folio is marked Uptodate after >> copying the symlink name, but the whole folio hasn’t been initialized, which >> seems unreasonable to me. Second, as I said before, using the 'PG_owner_2' >> flag to mark this uncommon case doesn’t seem worthwhile. Currently, IIUC the >> 'PG_owner_2' is only used by btrfs; if we ever want to remove the >> 'PG_owner_2', this uncommon symlink case shouldn’t block its removal. > > PG_owner_2 is aliased with PG_mappedtodisk [1], so it's used by every > filesystem which uses buffer_heads (whether mentioned in that filesystem > or not). btrfs was switched from using private_2 to using owner_2 > a little over a year ago. PG_owner_2 is not on the list of flags to be > removed; that's PG_private, PG_private_2 and PG_reserved. OK. Thanks for the explanation. I understand the plan.