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 7099C1C693; Wed, 24 Jul 2024 02:42:24 +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=1721788946; cv=none; b=JCa/CkO9gpP4B2IQTF0q7JM0cYN8B+DGvBmWlUHfOPnU963v3mRixOV1FDdGsU+YNFvsmyi34qNvWau5IQGJPRwc8DU76y5cccNcUpRdyq1JwkM56BsazN7n/JGnLcDYHJdFvwywt5vn6TMyW77o3+LEWRujLpmPmSr+ExruPAw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1721788946; c=relaxed/simple; bh=yNvMSyoNBzhV4cV7OJ5U9bGs1Z4iV7tBim6uaer3UbY=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=e++cEULBwlyUkef7MsSHmfhDpFjQSZ15dv9Pdxa+vMAWPsGHZGH9MT1nT/9GXbxeR0HPirEOPgefNNocIMWF5EZgWc+AUxvhcWekCnp8/n0r4HFMya7M53aVcPcuKtrP+gfXGkVlpzUiqPc8UvwQWAMiZvdfvGaxkH/FKAJkF3A= 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=hIL7ROVi; 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="hIL7ROVi" 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=JiDuGWepnTN0n5fOJFOEWm8213iD+rPD3GF635ET/sc=; b=hIL7ROVi5AnmZcVmdQRUZmuHtq YVU8jb+yGoZVKxE+oZcvlwLZqzcO2LBCBjaXWj3l/PXXXn5YqZkdMXasU923zdj/Nb1haFF4usofX ZIPG60eC1sFCmXiBHxjuFVulX/jkJWbQaN+727yqLDIrYgB9G3UgdpRARzPXRPiMoA+PgrAuj/q9v pZQcvppPlZb5ILdzXJQxFvTfv+Ke+8wXW3ejlylZyy+vECisfyUKFUeVywb8FjmiFR4LvHnfMLIs+ Dhf4UVXUGlNnIFFqPlCryS2PxCkKFCzDBwENRrxQuYH7Ck8fQ1nw48NOlu3rDHOtEtwmwEX/P4q7g 7uhve9mA==; Received: from willy by casper.infradead.org with local (Exim 4.97.1 #2 (Red Hat Linux)) id 1sWRxM-00000007R8m-00FS; Wed, 24 Jul 2024 02:42:20 +0000 Date: Wed, 24 Jul 2024 03:42:19 +0100 From: Matthew Wilcox To: Dave Chinner Cc: Jan Kara , David Howells , Alexander Viro , Christian Brauner , Jeff Layton , Gao Xiang , netfs@lists.linux.dev, linux-erofs@lists.ozlabs.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] vfs: Fix potential circular locking through setxattr() and removexattr() Message-ID: References: <2136178.1721725194@warthog.procyon.org.uk> <20240723104533.mznf3svde36w6izp@quack3> 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=us-ascii Content-Disposition: inline In-Reply-To: On Wed, Jul 24, 2024 at 11:34:57AM +1000, Dave Chinner wrote: > This is to prevent the deadlocks on upper->lower->upper and > lower->upper->lower filesystem recursion via GFP_KERNEL memory > allocation and reclaim recursing between the two filesystems. This > is especially relevant for filesystems with ->writepage methods that > can be called from direct reclaim. Hence allocations in this path > need to be at least NOFS to prevent recursion back into the upper > filesystem from writeback into the lower filesystem. FYI, we're making good progress on removing ->writepage. $ git grep '\.writepage\>.*=' fs/ceph/addr.c: .writepage = ceph_writepage, fs/ecryptfs/mmap.c: .writepage = ecryptfs_writepage, fs/f2fs/checkpoint.c: .writepage = f2fs_write_meta_page, fs/f2fs/data.c: .writepage = f2fs_write_data_page, fs/f2fs/node.c: .writepage = f2fs_write_node_page, fs/gfs2/aops.c: .writepage = gfs2_jdata_writepage, fs/gfs2/meta_io.c: .writepage = gfs2_aspace_writepage, fs/gfs2/meta_io.c: .writepage = gfs2_aspace_writepage, fs/hostfs/hostfs_kern.c: .writepage = hostfs_writepage, fs/nilfs2/inode.c: .writepage = nilfs_writepage, fs/nilfs2/mdt.c: .writepage = nilfs_mdt_write_page, fs/orangefs/inode.c: .writepage = orangefs_writepage, fs/vboxsf/file.c: .writepage = vboxsf_writepage, mm/shmem.c: .writepage = shmem_writepage, mm/swap_state.c: .writepage = swap_writepage, so mostly just the usual stragglers. I sent a series to fix up gfs2 earlier this week: https://lore.kernel.org/linux-fsdevel/20240719175105.788253-1-willy@infradead.org/