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 6358F21ADC6; Fri, 25 Apr 2025 20:01:11 +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=1745611273; cv=none; b=LJRYpaA7CykTRIUB+Kkk2LrGbbXCpoJJnns2WnvhK++4//eIlnQBnUiZLzlj2wvo36HljDdQA+gkDlLiVdH/+h9MwdVdYKZx40UR7bF8z6uZ9lWGgKrOXWWLlKkYnHZchUqRebjXEBB/epu3uQKlC+IeMG7bzL0jSZs6dvwNplE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1745611273; c=relaxed/simple; bh=n/1fR8HSszgJneX29axl6+BbOER/pnjQNSYcb0wrvXo=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=QtIXuQkIv0pRaqlSCFj3V8Nu0n40WpsDLX44QI80LdM15GOqNYMEANRatZnxliPdx302mzLlZwjueoQ48xj/UOu7wIX5HPFMt78MTxbBON8RmmVGkch3b3UNthi1fw0SRPWfBCR66jzZPuVJwXrpSEhnK1GUQnE7UX/QidLroCI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (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=r1rMBRHl; arc=none smtp.client-ip=90.155.50.34 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (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="r1rMBRHl" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=PCZojZ/zHTrseUyjrDFiaUsL6Zd8Ugb18vD3fXoqbck=; b=r1rMBRHl3w6e4SEbKmMjDlPgiP VuXgnMLo4Br5pl1kRwRoU5Uo10fpPpbtb4x8LDL/tTQtiLAzTfUi74AD1rL91Nn/AnHvQkAB0ENE7 Mf2n7TNe5CsRkUiOkTLbsUbiFVE2nvTxTjsJ2+J1SqF1AtLGMm9lQtRSJF2hXs0XGdkzN6huHZ6ef FgnqyCMw56YMQrkJKRmHJmyyTh2IHyCKeUXSEv1VzF3vwEUGqeIcSf4UaMOYEkUXL3Hzhby+dsxnI //kPM0KoX4hmj3YYlSdpWrXzQpbI6IR9ORQrDzbA30pKODNdHxixF8Ig0nktOGktFWtlprkJX4jfF nRIL5D+g==; Received: from willy by casper.infradead.org with local (Exim 4.98.2 #2 (Red Hat Linux)) id 1u8PEO-0000000FPAl-2mRE; Fri, 25 Apr 2025 20:01:04 +0000 Date: Fri, 25 Apr 2025 21:01:04 +0100 From: Matthew Wilcox To: I Hsin Cheng Cc: Jan Kara , syzbot+de1498ff3a934ac5e8b4@syzkaller.appspotmail.com, viro@zeniv.linux.org.uk, brauner@kernel.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, jfs-discussion@lists.sourceforge.net, shaggy@kernel.org, syzkaller-bugs@googlegroups.com, skhan@linuxfoundation.org, linux-kernel-mentees@lists.linux.dev Subject: Re: [RFC PATCH] fs/buffer: Handle non folio buffer case for drop_buffer() Message-ID: References: <66fcb7f9.050a0220.f28ec.04e8.GAE@google.com> <20250423023703.632613-1-richard120310@gmail.com> Precedence: bulk X-Mailing-List: linux-kernel-mentees@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: On Sat, Apr 26, 2025 at 12:52:42AM +0800, I Hsin Cheng wrote: > > Can you print more about the folio where this happened? In particular it > > would be interesting what's in folio->flags, folio->mapping->flags and > > folio->mapping->aops (resolved to a symbol). Because either the mapping has > > AS_RELEASE_ALWAYS set but then we should have ->releasepage handler, or > > have PG_Private bit set without buffers attached to a page but then again > > either ->releasepage should be set or there's some bug in fs/buffer.c which > > can set PG_Private without attaching buffers (I don't see where that could > > be). > > > > Hmm so I suppose when there're buffers attached, the PG_Private bit > should always be set in folio->flags or folio->mapping->flags or > folio->mapping->aops ? See folio_attach_private(). I am trying to get rid of PG_private, but we're not quite there yet. The other information may help track down what is going on.