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Commit ccf02aaf authored by Tejun Heo's avatar Tejun Heo Committed by Greg Kroah-Hartman
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kernfs: invoke kernfs_unmap_bin_file() directly from kernfs_deactivate() 



kernfs_unmap_bin_file() is supposed to unmap all memory mappings of
the target file before kernfs_remove() finishes; however, it currently
is being called from kernfs_addrm_finish() and has the same race
problem as the original implementation of deactivation when there are
multiple removers - only the remover which snatches the node to its
addrm_cxt->removed list is guaranteed to wait for its completion
before returning.

It can be easily fixed by moving kernfs_unmap_bin_file() invocation
from kernfs_addrm_finish() to kernfs_deactivated().  The function may
be called multiple times but that shouldn't do any harm.

Signed-off-by: default avatarTejun Heo <tj@kernel.org>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 35beab06

fs/kernfs/dir.c

+6 −4
Original line number Diff line number Diff line
@@ -177,9 +177,10 @@ void kernfs_put_active(struct kernfs_node *kn) 
 *	kernfs_deactivate - deactivate kernfs_node

 *	@kn: kernfs_node to deactivate

 *

 *	Deny new active references and drain existing ones.  Mutiple

 *	removers may invoke this function concurrently on @kn and all will

 *	return after deactivation and draining are complete.

 *	Deny new active references, drain existing ones and nuke all

 *	existing mmaps.  Mutiple removers may invoke this function

 *	concurrently on @kn and all will return after deactivation and

 *	draining are complete.

 */

static void kernfs_deactivate(struct kernfs_node *kn)

	__releases(&kernfs_mutex) __acquires(&kernfs_mutex)
@@ -213,6 +214,8 @@ static void kernfs_deactivate(struct kernfs_node *kn) 
		rwsem_release(&kn->dep_map, 1, _RET_IP_);

	}



	kernfs_unmap_bin_file(kn);



	mutex_lock(&kernfs_mutex);

}
@@ -493,7 +496,6 @@ void kernfs_addrm_finish(struct kernfs_addrm_cxt *acxt) 


		acxt->removed = kn->u.removed_list;



		kernfs_unmap_bin_file(kn);

		kernfs_put(kn);

	}

}