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b=KkPm2EowAckq6jWd8gZEXzwMkf2QfMHUiQMFIy70E3iGwRekztQJYTjbsOXAyNgxc UhZ8s6IeIsggwhrBv2pYCQ1fBM3JGQNTX/oMfFY6BP8O7yQ9C9yjdW8Nyl3O6wEkK4 YQ+smEWeXDZvwpGIJargk+S1j0E82kaQfJ/QzoGdAGJjF9BodZhuHXbn+XJ7nBWHmT fFXUzBi6mPZ7MMoK6TcqtjAUygbTH+3s4QkYAFxcGX1R8zClgalptG26Hc2tCPGNdz fZKzSti0QDZc3QQtCzlKxDyPFsh8Gl5TyLAJs1x+AfszKPhoCIDtB/04DnwfKIfMgu 2TlrKfL4qgGHg== Date: Mon, 14 Apr 2025 15:19:33 -0700 From: Luis Chamberlain To: Jan Kara Cc: brauner@kernel.org, tytso@mit.edu, adilger.kernel@dilger.ca, linux-ext4@vger.kernel.org, riel@surriel.com, dave@stgolabs.net, willy@infradead.org, hannes@cmpxchg.org, oliver.sang@intel.com, david@redhat.com, axboe@kernel.dk, hare@suse.de, david@fromorbit.com, djwong@kernel.org, ritesh.list@gmail.com, linux-fsdevel@vger.kernel.org, linux-block@vger.kernel.org, linux-mm@kvack.org, gost.dev@samsung.com, p.raghav@samsung.com, da.gomez@samsung.com, syzbot+f3c6fda1297c748a7076@syzkaller.appspotmail.com Subject: Re: [PATCH v2 1/8] migrate: fix skipping metadata buffer heads on migration Message-ID: References: <20250410014945.2140781-1-mcgrof@kernel.org> <20250410014945.2140781-2-mcgrof@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Stat-Signature: atwy5jmj5gznpsmo9h51zhqn4i33kbrb X-Rspam-User: X-Rspamd-Queue-Id: 565BF180012 X-Rspamd-Server: rspam08 X-HE-Tag: 1744669177-483092 X-HE-Meta: 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 hNeCDf9S IDUbDTIA4Rf1qVonp0YWBHjmqw4DE+bw+jAz6DJwxz5lsIDcvTrvcb3USkzTjelnT3Oc94+qFVz3Tr4GKLsJxaZIJNJxij5Iydgmww7uJiQo4s1Iese50FoFvVh5Bt0IoBJYwbuNDhv64fd8Uhf8BlOH2PJxlltpe6PqucMZOoI/3qF8G1OzF4aQZIWIbpDnrTRNXQBZzUhvf4uYVXOxAL+T3m+LqX5lqvyQ7BycrFU7RVDvgnlRQYNrC/fg3iUn/1cktNAD+5gl72xIjsnqT/NO3x/oum43d1lmblH9L+m9MxIT3RfURNH6j9A== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Mon, Apr 14, 2025 at 02:09:46PM -0700, Luis Chamberlain wrote: > On Thu, Apr 10, 2025 at 02:05:38PM +0200, Jan Kara wrote: > > > @@ -859,12 +862,12 @@ static int __buffer_migrate_folio(struct address_space *mapping, > > > } > > > bh = bh->b_this_page; > > > } while (bh != head); > > > + spin_unlock(&mapping->i_private_lock); > > > > No, you've just broken all simple filesystems (like ext2) with this patch. > > You can reduce the spinlock critical section only after providing > > alternative way to protect them from migration. So this should probably > > happen at the end of the series. > > So you're OK with this spin lock move with the other series in place? > > And so we punt the hard-to-reproduce corruption issue as future work > to do? Becuase the other alternative for now is to just disable > migration for jbd2: > > diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c > index 1dc09ed5d403..ef1c3ef68877 100644 > --- a/fs/ext4/inode.c > +++ b/fs/ext4/inode.c > @@ -3631,7 +3631,6 @@ static const struct address_space_operations ext4_journalled_aops = { > .bmap = ext4_bmap, > .invalidate_folio = ext4_journalled_invalidate_folio, > .release_folio = ext4_release_folio, > - .migrate_folio = buffer_migrate_folio_norefs, > .is_partially_uptodate = block_is_partially_uptodate, > .error_remove_folio = generic_error_remove_folio, > .swap_activate = ext4_iomap_swap_activate, BTW I ask because.. are your expectations that the next v3 series also be a target for Linus tree as part of a fix for this spinlock replacement? Luis