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Commit 4cd3bb10 authored by Hugh Dickins's avatar Hugh Dickins Committed by Linus Torvalds
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[PATCH] swap: move destroy_swap_extents calls 



sys_swapon's call to destroy_swap_extents on failure is made after the final
swap_list_unlock, which is faintly unsafe: another sys_swapon might already be
setting up that swap_info_struct.  Calling it earlier, before taking
swap_list_lock, is safe.  sys_swapoff's call to destroy_swap_extents was safe,
but likewise move it earlier, before taking the locks (once try_to_unuse has
completed, nothing can be needing the swap extents).

Signed-off-by: default avatarHugh Dickins <hugh@veritas.com>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent e2244ec2

mm/swapfile.c

+2 −2
Original line number Diff line number Diff line
@@ -1129,6 +1129,7 @@ asmlinkage long sys_swapoff(const char __user * specialfile) 
		swap_list_unlock();

		goto out_dput;

	}

	destroy_swap_extents(p);

	down(&swapon_sem);

	swap_list_lock();

	drain_mmlist();
@@ -1139,7 +1140,6 @@ asmlinkage long sys_swapoff(const char __user * specialfile) 
	swap_map = p->swap_map;

	p->swap_map = NULL;

	p->flags = 0;

	destroy_swap_extents(p);

	swap_device_unlock(p);

	swap_list_unlock();

	up(&swapon_sem);
@@ -1531,6 +1531,7 @@ asmlinkage long sys_swapon(const char __user * specialfile, int swap_flags) 
		set_blocksize(bdev, p->old_block_size);

		bd_release(bdev);

	}

	destroy_swap_extents(p);

bad_swap_2:

	swap_list_lock();

	swap_map = p->swap_map;
@@ -1540,7 +1541,6 @@ asmlinkage long sys_swapon(const char __user * specialfile, int swap_flags) 
	if (!(swap_flags & SWAP_FLAG_PREFER))

		++least_priority;

	swap_list_unlock();

	destroy_swap_extents(p);

	vfree(swap_map);

	if (swap_file)

		filp_close(swap_file, NULL);