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authorHuang Ying <ying.huang@intel.com>2017-05-03 14:54:39 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2017-05-03 15:52:10 -0700
commit2872bb2d0a4952ffb721e703555cb73d40b2c2f0 (patch)
tree6f7936193bf981d5aff8f1af8b723dd0c0dabb2b
parent0ef017d117d79eb765cb490a8d7e323752a13f4a (diff)
downloadlinux-2872bb2d0a4952ffb721e703555cb73d40b2c2f0.tar.bz2
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.com Signed-off-by: "Huang, Ying" <ying.huang@intel.com> Acked-by: Tim Chen <tim.c.chen@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--mm/swapfile.c6
1 files changed, 3 insertions, 3 deletions
diff --git a/mm/swapfile.c b/mm/swapfile.c
index 42fd620dcf4c..53b5881ee0d6 100644
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -672,6 +672,9 @@ checks:
else
goto done;
}
+ si->swap_map[offset] = usage;
+ inc_cluster_info_page(si, si->cluster_info, offset);
+ unlock_cluster(ci);
if (offset == si->lowest_bit)
si->lowest_bit++;
@@ -685,9 +688,6 @@ checks:
plist_del(&si->avail_list, &swap_avail_head);
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;
slots[n_ret++] = swp_entry(si->type, offset);