From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from casper.infradead.org (casper.infradead.org [90.155.50.34]) (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 4890A35BDCA for ; Tue, 6 Jan 2026 18:46:13 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=90.155.50.34 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1767725178; cv=none; b=CbDCWH+T1vf586H9IOn0HzB1n8kLUft4nj5Ib3L/rsu4qw/GIhC5vweVSc/p80qhSCOplSUrZ47RbFQk2vS9ly8cn+9t4BDfVOKksofvYp/FWw2Vz0OuQq3xDGdbaSSCbi1jzz6FgsZiPg4NkcYBgOCi2VSLKchyJEykURPshS8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1767725178; c=relaxed/simple; bh=lPX276eGaDNhEEJ1C302WSIt8nntAEFJAA3DW7XiQgI=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=PlpEC+gHfoYeSK2G9WriE7pg/siCw7ShKYi5IYcnNC9BeIgmoJzSAyNKlOPYf8eCwpL4JRis+4xI8I6JGgVLlLkTgdT9bT6N75wCLYVp5HOy1mXku4ijQL68IFxbF8Vp7vAeGwEpoBm0+FU8B7r55JLgl9dVSYHWryRyq/4hkwA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=infradead.org; spf=none smtp.mailfrom=infradead.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b=IARWE1zP; arc=none smtp.client-ip=90.155.50.34 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=infradead.org Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=infradead.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="IARWE1zP" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Transfer-Encoding: Content-Type:MIME-Version:References:Message-ID:Subject:Cc:To:From:Date: Sender:Reply-To:Content-ID:Content-Description; bh=Wo2o+JALBU6VBsZm8lcVzlOAHsqn/+GMFk5NcFxlXaM=; b=IARWE1zPOdFKJHoMAVzT6KZBBy gA0djuK2uGibigJfm3JoBK50ngrNEDi/Rje3Fgvrib7URrln1rgFzWnIJ6dlygys0v9R+QIC3vXue F1slxyym3DrOXusXNKSWHSkd1zH/ZPKtydzPVNgceekGX4Xxb6j4HtMzDEObT8KXonwAk4x4F3CDO Q9M7RCTOqHTEd05uAL5AuTPnY6y0orxb1YMQrbVcW1HWoVWtzLQzKLHMvzjd//4V+/oxiE72VVBco hCq3JUZKbMsK/l46Pe3L0tPZG3uhl+Qka8cKormNffICx7hxI/bdwpUJqXQCRSXk6cmTSjlR05a6u vM1BIYAQ==; Received: from willy by casper.infradead.org with local (Exim 4.98.2 #2 (Red Hat Linux)) id 1vdC4F-0000000CJZ3-2085; Tue, 06 Jan 2026 18:46:07 +0000 Date: Tue, 6 Jan 2026 18:46:07 +0000 From: Matthew Wilcox To: Baolin Wang 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 Subject: Re: [PATCH] mm/shmem: fix uninitialized folio in shmem_symlink Message-ID: References: <20251224094027.65842-1-21cnbao@gmail.com> <2b12f63b-ceab-4d3e-a06f-f41e6b1b2d23@linux.alibaba.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <2b12f63b-ceab-4d3e-a06f-f41e6b1b2d23@linux.alibaba.com> 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. [1] include/linux/page-flags.h: PG_mappedtodisk = PG_owner_2,