From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) (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 02A442EBB8C for ; Mon, 2 Feb 2026 18:34:22 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.133.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1770057264; cv=none; b=PrlFzIvH+b1VXr9U7UgxuWMOhfVRGArahCB7k0bjBsYN0NyBQr7BqyZjHi9XavYOgoF8jwJSp3vH25Z3OmSARrx9Brztncbn00i7571P2SMS0G3S77t5wbUmK2VtEdr7uzz5jsY4POacID0eKyDkWgIug56xRmUkhu13gCDPzHQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1770057264; c=relaxed/simple; bh=st2gunRIFmQ1p7JJtTsaRS1xasxYmMpqzB/ZRL8fUYA=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=RZLYSVuCY9JmwXhyUlyYzgB0phfgvBdPH1wa+/nAU0YjXZFtw/GWmd0YLxRMeLEXG9qUlraxWP8Rc/47LVLY+kRrStQt04RTZT0xnAK/O3Bkd8bwgTWqIfXUoQ+15PWW2QJL9lEvXJNzBniDE3OOgpmEIkPO/djHTrxfY+UsEAU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=QX6zh5En; arc=none smtp.client-ip=170.10.133.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="QX6zh5En" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1770057262; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=OWPieg0Bvkioyg2EeqBdekXZF/DTC3okjM25F8ZVq1w=; b=QX6zh5EnFDYpp67FOEj/pw3mjA9tuLryveWn70A+eqnUcCpNh7LGQjKWVPIDOX8gq9xEQN /vOaQ8eeNOZJ0A7+2p3BWKBQObdFvW0zwv8FgIew+oDgR5VENdeVc/pAjet3H5ppE8Qs5n yC9RAD0tXEQZGI+YhuBEVPBr7DqBrqY= Received: from mx-prod-mc-01.mail-002.prod.us-west-2.aws.redhat.com (ec2-54-186-198-63.us-west-2.compute.amazonaws.com [54.186.198.63]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-54-1sc3xcvPNBi-w4c044jdtA-1; Mon, 02 Feb 2026 13:34:18 -0500 X-MC-Unique: 1sc3xcvPNBi-w4c044jdtA-1 X-Mimecast-MFC-AGG-ID: 1sc3xcvPNBi-w4c044jdtA_1770057257 Received: from mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.111]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-01.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id D18551954204; Mon, 2 Feb 2026 18:34:16 +0000 (UTC) Received: from bfoster (unknown [10.22.88.110]) by mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id B90631800577; Mon, 2 Feb 2026 18:34:13 +0000 (UTC) Date: Mon, 2 Feb 2026 13:34:11 -0500 From: Brian Foster To: Christoph Hellwig Cc: Matthew Wilcox , Piyush Patle , brauner@kernel.org, djwong@kernel.org, linux-xfs@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, syzbot+bd5ca596a01d01bfa083@syzkaller.appspotmail.com Subject: Re: [PATCH] iomap: handle iterator position advancing beyond current mapping Message-ID: References: <20260202130044.567989-1-piyushpatle228@gmail.com> Precedence: bulk X-Mailing-List: linux-fsdevel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.111 On Mon, Feb 02, 2026 at 08:05:48AM -0800, Christoph Hellwig wrote: > On Mon, Feb 02, 2026 at 03:35:39PM +0000, Matthew Wilcox wrote: > > On Mon, Feb 02, 2026 at 06:48:50AM -0800, Christoph Hellwig wrote: > > > On Mon, Feb 02, 2026 at 06:30:44PM +0530, Piyush Patle wrote: > > > > Closes: https://syzkaller.appspot.com/bug?id=bd5ca596a01d01bfa083 > > > > > > This link doesn't work. And the commit log has zero details of what's > > > happening either. > > > > Looks like this one: > > > > https://syzkaller.appspot.com/bug?extid=bd5ca596a01d01bfa083 > > > > but there's no reproducer. Looks like it's through the blockdev rather > > than a filesystem being involved. > > Let's wait for a reproducer. The fix looks incorrect for anything I > could think of, so I'd rather fix a real bug. Given that lack of > reproducer I'm also not confident that it fixes anything. The fact > that the Fixes tag points to a merge commit doesn't really increase > the trust I have in it either. > > +1 to this, FWIW. I've had that syzbot report marked in my inbox expecting (hoping..) it would eventually spit out a reproducer to help better characterize the cause. This patch just appears to copy the warning check and force a lookup cycle before we trigger it, which I don't think is doing us any favors. At minimum we should have an understanding of precisely how this happens. Brian