On Mon, Feb 22, 2021 at 06:16:26PM +0100, Jan Kara wrote: > Syzbot is reporting that ext4 can enter fs reclaim from kvmalloc() while > the transaction is started like: > > fs_reclaim_acquire+0x117/0x150 mm/page_alloc.c:4340 > might_alloc include/linux/sched/mm.h:193 [inline] > slab_pre_alloc_hook mm/slab.h:493 [inline] > slab_alloc_node mm/slub.c:2817 [inline] > __kmalloc_node+0x5f/0x430 mm/slub.c:4015 > kmalloc_node include/linux/slab.h:575 [inline] > kvmalloc_node+0x61/0xf0 mm/util.c:587 > kvmalloc include/linux/mm.h:781 [inline] > ext4_xattr_inode_cache_find fs/ext4/xattr.c:1465 [inline] > ext4_xattr_inode_lookup_create fs/ext4/xattr.c:1508 [inline] > ext4_xattr_set_entry+0x1ce6/0x3780 fs/ext4/xattr.c:1649 > ext4_xattr_ibody_set+0x78/0x2b0 fs/ext4/xattr.c:2224 > ext4_xattr_set_handle+0x8f4/0x13e0 fs/ext4/xattr.c:2380 > ext4_xattr_set+0x13a/0x340 fs/ext4/xattr.c:2493 > > This should be impossible since transaction start sets PF_MEMALLOC_NOFS. > Add some assertions to the code to catch if something isn't working as > expected early. > > Link: https://lore.kernel.org/linux-ext4/000000000000563a0205bafb7970@xxxxxxxxxx/ > Signed-off-by: Jan Kara <jack@xxxxxxx> Thanks, applied. - Ted
