diff options
| author | Dongsheng Yang <dongsheng.yang@easystack.cn> | 2020-10-01 14:50:43 +0800 |
|---|---|---|
| committer | Jens Axboe <axboe@kernel.dk> | 2020-10-02 14:25:29 -0600 |
| commit | 7e59c506c338d1e42ed19f24f1a737aff8b18fc3 (patch) | |
| tree | af5729bacc3bfe4e36f29700d153d121b92700cf | |
| parent | a58e88bfdc4d527f99827b8d66ecf68d05c3ac87 (diff) | |
bcache: check c->root with IS_ERR_OR_NULL() in mca_reserve()
In mca_reserve(c) macro, we are checking root whether is NULL or not.
But that's not enough, when we read the root node in run_cache_set(),
if we got an error in bch_btree_node_read_done(), we will return
ERR_PTR(-EIO) to c->root.
And then we will go continue to unregister, but before calling
unregister_shrinker(&c->shrink), there is a possibility to call
bch_mca_count(), and we would get a crash with call trace like that:
[ 2149.876008] Unable to handle kernel NULL pointer dereference at virtual address 00000000000000b5
... ...
[ 2150.598931] Call trace:
[ 2150.606439] bch_mca_count+0x58/0x98 [escache]
[ 2150.615866] do_shrink_slab+0x54/0x310
[ 2150.624429] shrink_slab+0x248/0x2d0
[ 2150.632633] drop_slab_node+0x54/0x88
[ 2150.640746] drop_slab+0x50/0x88
[ 2150.648228] drop_caches_sysctl_handler+0xf0/0x118
[ 2150.657219] proc_sys_call_handler.isra.18+0xb8/0x110
[ 2150.666342] proc_sys_write+0x40/0x50
[ 2150.673889] __vfs_write+0x48/0x90
[ 2150.681095] vfs_write+0xac/0x1b8
[ 2150.688145] ksys_write+0x6c/0xd0
[ 2150.695127] __arm64_sys_write+0x24/0x30
[ 2150.702749] el0_svc_handler+0xa0/0x128
[ 2150.710296] el0_svc+0x8/0xc
Signed-off-by: Dongsheng Yang <dongsheng.yang@easystack.cn>
Signed-off-by: Coly Li <colyli@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
| -rw-r--r-- | drivers/md/bcache/btree.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/drivers/md/bcache/btree.c b/drivers/md/bcache/btree.c index 3d8bd0692af3..ae7611fa42bf 100644 --- a/drivers/md/bcache/btree.c +++ b/drivers/md/bcache/btree.c @@ -514,7 +514,7 @@ static void bch_btree_leaf_dirty(struct btree *b, atomic_t *journal_ref) * mca -> memory cache */ -#define mca_reserve(c) (((c->root && c->root->level) \ +#define mca_reserve(c) (((!IS_ERR_OR_NULL(c->root) && c->root->level) \ ? c->root->level : 1) * 8 + 16) #define mca_can_free(c) \ max_t(int, 0, c->btree_cache_used - mca_reserve(c)) |