From d611b22f1a5ddd0823e9d6a30bac91219f800e41 Mon Sep 17 00:00:00 2001 From: Ryusuke Konishi Date: Wed, 30 Mar 2011 11:49:20 +0900 Subject: [PATCH] nilfs2: fix oops due to a bad aops initialization Nilfs in 2.6.39-rc1 hit the following oops: BUG: unable to handle kernel NULL pointer dereference at 0000000000000048 IP: [] try_to_release_page+0x2a/0x3d PGD 234cb6067 PUD 234c72067 PMD 0 Oops: 0000 [#1] SMP Process truncate (pid: 10995, threadinfo ffff8802353c2000, task ffff880234cfa000) Stack: ffff8802333c77b8 ffffffff810b64b0 0000000000003802 ffffffffa0052cca 0000000000000000 ffff8802353c3b58 0000000000000000 ffff8802353c3b58 0000000000000001 0000000000000000 ffffea0007b92308 ffffea0007b92308 Call Trace: [] ? invalidate_inode_pages2_range+0x15f/0x273 [] ? nilfs_palloc_get_block+0x2d/0xaf [nilfs2] [] ? bit_waitqueue+0x14/0xa1 [] ? wake_up_bit+0x10/0x20 [] ? nilfs_forget_buffer+0x66/0x7a [nilfs2] [] ? nilfs_btree_concat_left+0x5c/0x77 [nilfs2] [] ? nilfs_btree_delete+0x395/0x3cf [nilfs2] [] ? nilfs_bmap_do_delete+0x6e/0x79 [nilfs2] [] ? nilfs_btree_last_key+0x14b/0x15e [nilfs2] [] ? nilfs_bmap_truncate+0x2f/0x83 [nilfs2] [] ? nilfs_bmap_last_key+0x35/0x62 [nilfs2] [] ? nilfs_truncate_bmap+0x6b/0xc7 [nilfs2] [] ? nilfs_truncate+0x79/0xe4 [nilfs2] [] ? vmtruncate+0x33/0x3b [] ? nilfs_setattr+0x4d/0x8c [nilfs2] [] ? do_page_fault+0x31b/0x356 [] ? notify_change+0x17d/0x262 [] ? do_truncate+0x65/0x80 [] ? sys_ftruncate+0xf1/0xf6 [] ? system_call_fastpath+0x16/0x1b Code: c3 48 83 ec 08 48 8b 17 48 8b 47 18 80 e2 01 75 04 0f 0b eb fe 48 8b 17 80 e6 20 74 05 31 c0 41 59 c3 48 85 c0 74 11 48 8b 40 58 8b 40 48 48 85 c0 74 04 41 58 ff e0 59 e9 b1 b5 05 00 41 54 RIP [] try_to_release_page+0x2a/0x3d RSP CR2: 0000000000000048 This oops was brought in by the change "block: remove per-queue plugging" (commit: 7eaceaccab5f40bb). It initializes mapping->a_ops with a NULL pointer for some pages in nilfs (e.g. btree node pages), but mm code doesn't NULL pointer checks against mapping->a_ops. (the check is done for each callback function) This corrects the aops initialization and fixes the oops. Signed-off-by: Ryusuke Konishi Acked-by: Jens Axboe --- fs/nilfs2/page.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/fs/nilfs2/page.c b/fs/nilfs2/page.c index 4d2a1ee0eb47..9d2dc6b4348e 100644 --- a/fs/nilfs2/page.c +++ b/fs/nilfs2/page.c @@ -495,12 +495,14 @@ unsigned nilfs_page_count_clean_buffers(struct page *page, void nilfs_mapping_init(struct address_space *mapping, struct backing_dev_info *bdi) { + static const struct address_space_operations empty_aops; + mapping->host = NULL; mapping->flags = 0; mapping_set_gfp_mask(mapping, GFP_NOFS); mapping->assoc_mapping = NULL; mapping->backing_dev_info = bdi; - mapping->a_ops = NULL; + mapping->a_ops = &empty_aops; } /* -- 2.20.1