From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=13.77.154.182 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1793640259; b=2qFn+DYIwNAliGUywPMY19ZWkYwYMez/hodNayfeEv/CyDfGI6+bsZ+/GnU/mlJ3e5rb 7EplpAO8wXBPSCoBmwWnYnzYa8VpeZtQGxsRXj5nFgM7F8xam3aHz3BFt3J47OJ+yMs/3 bQOxzSfFb8fBfKGoX3K21M21Il5iOycWoC4PfdKs9+6Ve3POnWmm/oGrTC5a9XmuLhI/+ rwVHR8M26cOcFQrZ8MJ2tiaT3FO4WXaUvq2L9OYy9T+3+Y/aIOFtnC6mNWVLd1Z+tfXkb KZ1iOslB8Ev3oyF3R35gkzrazZb/GfowVUkXUnG4VROnG7n8GPFXHNGi2msGUq+yhdw== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793640259; h=DMARC-Filter:Received:DKIM-Filter:DKIM-Signature:Message-ID:Date: MIME-Version:User-Agent:Subject:To:Cc:References:Content-Language: From:In-Reply-To:Content-Type:Content-Transfer-Encoding:X-Spam-Status: X-Spam-Checker-Version; bh=BBwVsAGDI2P1A8Xz+TjsiWaX1Q+VUcv4TW1ekog7gog=; b=WQZYylYUhCv37wxJK7HX+ruwbJLieSnctyYcdMdH2E6Uozy/D7Euk1HiRTvFVt5t9Lpc QVJwSgHosMRAWaDKIxhTCHQGnagjdErtrSCZAY0cJAlG3GZcAFiZ3Nx/51i9eNG+GeLnG BFV5GSyQoOpM9HeXMCYDfSebNRgLiZ7jKmZ7QSYnlEC5vPZv1EK5wC9SYQASf2C5tqIwp 0bwRXQv/dnBLqCpbtIF3texdUC05A8tuxnLuTnSOuQasqNgrf5CP+voBOETDNdXv8PPdm BET0gOOibhtodkPsxsyskgTT2aBhpDugmY/jreSBUrUNSJAgekUBoy/hJLnXcGMDD/A== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass header.from=linux.microsoft.com; spf=pass smtp.mailfrom=linux.microsoft.com; dkim=pass header.d=linux.microsoft.com header.i=@linux.microsoft.com header.a=rsa-sha256 header.s=default header.b="Ny9x/sna"; arc=none smtp.remote-ip=13.77.154.182 Received: from linux.microsoft.com (linux.microsoft.com [13.77.154.182]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 6536B606B907; Mon, 2 Nov 2026 17:24:19 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.2 smtp.subspace.kernel.org 6536B606B907 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.microsoft.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.microsoft.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key, unprotected) header.d=linux.microsoft.com header.i=@linux.microsoft.com header.a=rsa-sha256 header.s=default header.b=Ny9x/sna Received: from [192.168.1.70] (unknown [4.194.122.170]) by linux.microsoft.com (Postfix) with ESMTPSA id 0090020B7166; Mon, 2 Nov 2026 09:24:02 -0800 (PST) DKIM-Filter: OpenDKIM Filter v2.11.0 linux.microsoft.com 0090020B7166 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.microsoft.com; s=default; t=1793640244; bh=BBwVsAGDI2P1A8Xz+TjsiWaX1Q+VUcv4TW1ekog7gog=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=Ny9x/snajR4zT66QEVZqO52W0eHruSPt3TFkBD8xarvPIvaqMl/iFPnPggCvN4Ds6 +/LcieDxmQqtzktl0ypU2/GTpoT+v1vOU5Lwjmr5Hxd6DZKXHuvTWJZroZun8PxVYa nto8Qxc5tXEeLmU3XWzeJfASzddzgvUbP3Icqob8= Message-ID: Date: Mon, 2 Nov 2026 22:54:13 +0530 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 6.1] ext4: honor NULL returns from __filemap_get_folio() To: Matthew Wilcox Cc: Theodore Ts'o , Andreas Dilger , Sasha Levin , stable@vger.kernel.org, linux-ext4@vger.kernel.org, linux-kernel@vger.kernel.org References: <20261102163341.2170232-1-namjain@linux.microsoft.com> Content-Language: en-US From: Naman Jain In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 11/2/2026 10:39 PM, Matthew Wilcox wrote: > On Mon, Nov 02, 2026 at 04:33:41PM +0000, Naman Jain wrote: >> The bitmap and buddy folio conversions assume that >> __filemap_get_folio() returns error pointers. In Linux 6.1, however, >> it returns NULL both when a non-creating lookup misses and when folio >> creation fails. >> >> A cache miss therefore passes the IS_ERR() check and reaches >> folio_test_uptodate(NULL) in ext4_mb_load_buddy_gfp(). Creating-lookup >> failures can also dereference NULL in its slow paths and in >> ext4_mb_get_buddy_page_lock(). >> >> Restore NULL checks at all six lookup sites and return -ENOMEM when a >> creating lookup fails. Preserve the folio locking and migration checks >> without changing the global filemap API. >> >> Fixes: d34e4fd4e73f ("ext4: convert bd_bitmap_page to bd_bitmap_folio") >> Fixes: 862483175d3d ("ext4: convert bd_buddy_page to bd_buddy_folio") >> Cc: stable@vger.kernel.org # 6.1.x >> Signed-off-by: Naman Jain > > Elliot beat you to it: > > https://lore.kernel.org/linux-ext4/20261102-ext4-ntfs3-null-folio-v1-0-4fd91ee23a4a@elliotjb.com/ > > Care to drop a R-b on his series? Done. I actually checked LKML in the morning for this :) Regards, Naman