From: Huang Ying <[email protected]> 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.
Signed-off-by: "Huang, Ying" <[email protected]> Acked-by: Tim Chen <[email protected]> --- mm/swapfile.c | 6 +++--- 1 file 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 @@ static int scan_swap_map_slots(struct swap_info_struct *si, 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 @@ static int scan_swap_map_slots(struct swap_info_struct *si, 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); -- 2.11.0
