The patch titled
Subject: mm/swap: avoid a xa load for swapout path
has been added to the -mm mm-unstable branch. Its filename is
mm-swap-avoid-a-xa-load-for-swapout-path.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-swap-avoid-a-xa-load-for-swapout-path.patch
This patch will later appear in the mm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: Kairui Song <kasong@xxxxxxxxxxx>
Subject: mm/swap: avoid a xa load for swapout path
Date: Tue, 17 Oct 2023 09:17:28 +0800
A variable is never used for swapout path (shadowp is NULL) and compiler
is unable to optimize out the unneeded load since it's a function call.
The was introduced by 3852f6768ede ("mm/swapcache: support to handle the
shadow entries").
Link: https://lkml.kernel.org/r/20231017011728.37508-1-ryncsn@xxxxxxxxx
Signed-off-by: Kairui Song <kasong@xxxxxxxxxxx>
Reviewed-by: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
Cc: Huang Ying <ying.huang@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/swap_state.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
--- a/mm/swap_state.c~mm-swap-avoid-a-xa-load-for-swapout-path
+++ a/mm/swap_state.c
@@ -111,9 +111,9 @@ int add_to_swap_cache(struct folio *foli
goto unlock;
for (i = 0; i < nr; i++) {
VM_BUG_ON_FOLIO(xas.xa_index != idx + i, folio);
- old = xas_load(&xas);
- if (xa_is_value(old)) {
- if (shadowp)
+ if (shadowp) {
+ old = xas_load(&xas);
+ if (xa_is_value(old))
*shadowp = old;
}
xas_store(&xas, folio);
_
Patches currently in -mm which might be from kasong@xxxxxxxxxxx are
mm-oom_killer-simplify-oom-killer-info-dump-helper.patch
mm-swap-avoid-a-xa-load-for-swapout-path.patch
