Re: [PATCH 1/8] ext4: free the sbi after a grace period
flat view
From: sashiko-bot@kernel.org
Date: 2026-10-09 22:04:37
Also in:
linux-ext4
ext4_get_link() follows a symlink that keeps its target in a data block
in rcu pathwalk mode with ext4_getblk(EXT4_GET_BLOCKS_CACHED_NOWAIT).
That reads s_mount_state in the ASSERT() of ext4_getblk() and again in
ext4_es_lookup_extent(), and the lookup bumps the extent status hit or
miss counter, all through sb->s_fs_info.
ext4_put_super() destroys those counters, clears sb->s_fs_info and frees
the sbi without waiting for a grace period. A pathwalk that is still in
ext4_get_link() when the last reference to the mount goes away then
dereferences a NULL s_fs_info, the freed sbi or the destroyed percpu
counters.
With a pathwalk held up in ext4_get_link() while the last reference
goes away:
[ ... ]
in ext4_put_super(), the counters go with the sbi.
Fixes: 6493792d3299 ("ext4: convert symlink external data block mapping to bdev")
Cc: <redacted>
Signed-off-by: Christian Brauner (Amutable) <brauner@kernel.org>Sashiko has reviewed this patch and found no issues. It looks great! -- Sashiko AI review · https://sashiko.dev/#/patchset/20261009-work-fixes-rcu-v1-0-7446d2d335e6@kernel.org?part=1