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| author | Jan Kara <jack@suse.cz> | 2021-02-22 18:16:26 +0100 |
|---|---|---|
| committer | Theodore Ts'o <tytso@mit.edu> | 2021-03-06 11:56:10 -0500 |
| commit | 163f0ec1df33cf468509ff38cbcbb5eb0d7fac60 (patch) | |
| tree | 5f7a0f4d575d4644af3366688e6fa9dd77257fe4 /fs/ext4/xattr.c | |
| parent | efc61345274d6c7a46a0570efbc916fcbe3e927b (diff) | |
| download | lwn-163f0ec1df33cf468509ff38cbcbb5eb0d7fac60.tar.gz lwn-163f0ec1df33cf468509ff38cbcbb5eb0d7fac60.zip | |
ext4: add reclaim checks to xattr code
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@google.com/
Signed-off-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20210222171626.21884-1-jack@suse.cz
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Diffstat (limited to 'fs/ext4/xattr.c')
| -rw-r--r-- | fs/ext4/xattr.c | 4 |
1 files changed, 4 insertions, 0 deletions
diff --git a/fs/ext4/xattr.c b/fs/ext4/xattr.c index 372208500f4e..083c95126781 100644 --- a/fs/ext4/xattr.c +++ b/fs/ext4/xattr.c @@ -1462,6 +1462,9 @@ ext4_xattr_inode_cache_find(struct inode *inode, const void *value, if (!ce) return NULL; + WARN_ON_ONCE(ext4_handle_valid(journal_current_handle()) && + !(current->flags & PF_MEMALLOC_NOFS)); + ea_data = kvmalloc(value_len, GFP_KERNEL); if (!ea_data) { mb_cache_entry_put(ea_inode_cache, ce); @@ -2327,6 +2330,7 @@ ext4_xattr_set_handle(handle_t *handle, struct inode *inode, int name_index, error = -ENOSPC; goto cleanup; } + WARN_ON_ONCE(!(current->flags & PF_MEMALLOC_NOFS)); } error = ext4_reserve_inode_write(handle, inode, &is.iloc); |