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Commit 770d42ff authored by Tong Zhang's avatar Tong Zhang Committed by Greg Kroah-Hartman
Browse files

dax: make sure inodes are flushed before destroy cache 



[ Upstream commit a7e8de822e0b1979f08767c751f6c8a9c1d4ad86 ]

A bug can be triggered by following command

$ modprobe nd_pmem && modprobe -r nd_pmem

[   10.060014] BUG dax_cache (Not tainted): Objects remaining in dax_cache on __kmem_cache_shutdown()
[   10.060938] Slab 0x0000000085b729ac objects=9 used=1 fp=0x000000004f5ae469 flags=0x200000000010200(slab|head|node)
[   10.062433] Call Trace:
[   10.062673]  dump_stack_lvl+0x34/0x44
[   10.062865]  slab_err+0x90/0xd0
[   10.063619]  __kmem_cache_shutdown+0x13b/0x2f0
[   10.063848]  kmem_cache_destroy+0x4a/0x110
[   10.064058]  __x64_sys_delete_module+0x265/0x300

This is caused by dax_fs_exit() not flushing inodes before destroy cache.
To fix this issue, call rcu_barrier() before destroy cache.

Signed-off-by: default avatarTong Zhang <ztong0001@gmail.com>
Reviewed-by: default avatarIra Weiny <ira.weiny@intel.com>
Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20220212071111.148575-1-ztong0001@gmail.com


Fixes: 7b6be844 ("dax: refactor dax-fs into a generic provider of 'struct dax_device' instances")
Signed-off-by: default avatarDan Williams <dan.j.williams@intel.com>
Signed-off-by: default avatarSasha Levin <sashal@kernel.org>
parent c10980c5

drivers/dax/super.c

+1 −0
Original line number Original line Diff line number Diff line
@@ -691,6 +691,7 @@ static int dax_fs_init(void) 
static void dax_fs_exit(void)

static void dax_fs_exit(void)

{

{

	kern_unmount(dax_mnt);

	kern_unmount(dax_mnt);

	rcu_barrier();

	kmem_cache_destroy(dax_cache);

	kmem_cache_destroy(dax_cache);

}

}