Commit 2872bb2d authored by Huang Ying's avatar Huang Ying Committed by Linus Torvalds

mm, swap: avoid lock swap_avail_lock when held cluster lock

Cluster lock is used to protect the swap_cluster_info and corresponding
elements in swap_info_struct->swap_map[].  But it is found that now in
scan_swap_map_slots(), swap_avail_lock may be acquired when cluster lock
is held.  This does no good except making the locking more complex and
improving the potential locking contention, because the
swap_info_struct->lock is used to protect the data structure operated in
the code already.  Fix this via moving the corresponding operations in
scan_swap_map_slots() out of cluster lock.

Link: http://lkml.kernel.org/r/20170317064635.12792-3-ying.huang@intel.comSigned-off-by: default avatar"Huang, Ying" <ying.huang@intel.com>
Acked-by: default avatarTim Chen <tim.c.chen@intel.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 0ef017d1
...@@ -672,6 +672,9 @@ static int scan_swap_map_slots(struct swap_info_struct *si, ...@@ -672,6 +672,9 @@ static int scan_swap_map_slots(struct swap_info_struct *si,
else else
goto done; goto done;
} }
si->swap_map[offset] = usage;
inc_cluster_info_page(si, si->cluster_info, offset);
unlock_cluster(ci);
if (offset == si->lowest_bit) if (offset == si->lowest_bit)
si->lowest_bit++; si->lowest_bit++;
...@@ -685,9 +688,6 @@ static int scan_swap_map_slots(struct swap_info_struct *si, ...@@ -685,9 +688,6 @@ static int scan_swap_map_slots(struct swap_info_struct *si,
plist_del(&si->avail_list, &swap_avail_head); plist_del(&si->avail_list, &swap_avail_head);
spin_unlock(&swap_avail_lock); spin_unlock(&swap_avail_lock);
} }
si->swap_map[offset] = usage;
inc_cluster_info_page(si, si->cluster_info, offset);
unlock_cluster(ci);
si->cluster_next = offset + 1; si->cluster_next = offset + 1;
slots[n_ret++] = swp_entry(si->type, offset); slots[n_ret++] = swp_entry(si->type, offset);
......
Markdown is supported
0%
or
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment