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authorMiklos Szeredi <mszeredi@suse.cz>2011-02-23 07:49:47 -0500
committerLinus Torvalds <torvalds@linux-foundation.org>2011-02-23 22:52:52 -0500
commit2aa15890f3c191326678f1bd68af61ec6b8753ec (patch)
tree347f5fdcd0678b12be92f266cd2a5e7a74749403 /fs/nilfs2/mdt.c
parent78794b2cdeac37ac1fd950fc9c4454b56d88ac03 (diff)
mm: prevent concurrent unmap_mapping_range() on the same inode
Michael Leun reported that running parallel opens on a fuse filesystem can trigger a "kernel BUG at mm/truncate.c:475" Gurudas Pai reported the same bug on NFS. The reason is, unmap_mapping_range() is not prepared for more than one concurrent invocation per inode. For example: thread1: going through a big range, stops in the middle of a vma and stores the restart address in vm_truncate_count. thread2: comes in with a small (e.g. single page) unmap request on the same vma, somewhere before restart_address, finds that the vma was already unmapped up to the restart address and happily returns without doing anything. Another scenario would be two big unmap requests, both having to restart the unmapping and each one setting vm_truncate_count to its own value. This could go on forever without any of them being able to finish. Truncate and hole punching already serialize with i_mutex. Other callers of unmap_mapping_range() do not, and it's difficult to get i_mutex protection for all callers. In particular ->d_revalidate(), which calls invalidate_inode_pages2_range() in fuse, may be called with or without i_mutex. This patch adds a new mutex to 'struct address_space' to prevent running multiple concurrent unmap_mapping_range() on the same mapping. [ We'll hopefully get rid of all this with the upcoming mm preemptibility series by Peter Zijlstra, the "mm: Remove i_mmap_mutex lockbreak" patch in particular. But that is for 2.6.39 ] Signed-off-by: Miklos Szeredi <mszeredi@suse.cz> Reported-by: Michael Leun <lkml20101129@newton.leun.net> Reported-by: Gurudas Pai <gurudas.pai@oracle.com> Tested-by: Gurudas Pai <gurudas.pai@oracle.com> Acked-by: Hugh Dickins <hughd@google.com> Cc: stable@kernel.org Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'fs/nilfs2/mdt.c')
-rw-r--r--fs/nilfs2/mdt.c4
1 files changed, 2 insertions, 2 deletions
diff --git a/fs/nilfs2/mdt.c b/fs/nilfs2/mdt.c
index 6a0e2a189f60..a0babd2bff6a 100644
--- a/fs/nilfs2/mdt.c
+++ b/fs/nilfs2/mdt.c
@@ -454,9 +454,9 @@ int nilfs_mdt_setup_shadow_map(struct inode *inode,
454 struct backing_dev_info *bdi = inode->i_sb->s_bdi; 454 struct backing_dev_info *bdi = inode->i_sb->s_bdi;
455 455
456 INIT_LIST_HEAD(&shadow->frozen_buffers); 456 INIT_LIST_HEAD(&shadow->frozen_buffers);
457 nilfs_mapping_init_once(&shadow->frozen_data); 457 address_space_init_once(&shadow->frozen_data);
458 nilfs_mapping_init(&shadow->frozen_data, bdi, &shadow_map_aops); 458 nilfs_mapping_init(&shadow->frozen_data, bdi, &shadow_map_aops);
459 nilfs_mapping_init_once(&shadow->frozen_btnodes); 459 address_space_init_once(&shadow->frozen_btnodes);
460 nilfs_mapping_init(&shadow->frozen_btnodes, bdi, &shadow_map_aops); 460 nilfs_mapping_init(&shadow->frozen_btnodes, bdi, &shadow_map_aops);
461 mi->mi_shadow = shadow; 461 mi->mi_shadow = shadow;
462 return 0; 462 return 0;