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mm/swapfile.c: introduce function alloc_swap_scan_list()

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Patch series "mm/swapfile.c and swap.h cleanup", v3.

This patch series, which builds on Kairui's swap improve cluster scan series.
https://lore.kernel.org/linux-mm/20250806161748.76651-1-ryncsn@gmail.com/

It introduces a new function, alloc_swap_scan_list(), for swapfile.c.

It also cleans up swap.h by removing comments that reference fields that
have been deleted.

There are no functional changes in this two-patch series.


This patch (of 2):

alloc_swap_scan_list() will scan the whole list or the first cluster.

This reduces the repeat patterns of isolating a cluster then scanning that
cluster.  As a result, cluster_alloc_swap_entry() is shorter and
shallower.

No functional change.

Link: https://lkml.kernel.org/r/20250812-swap-scan-list-v3-0-6d73504d267b@kernel.org
Link: https://lkml.kernel.org/r/20250812-swap-scan-list-v3-1-6d73504d267b@kernel.org
Signed-off-by: Chris Li <chrisl@kernel.org>
Reviewed-by: Kairui Song <kasong@tencent.com>
Acked-by: Nhat Pham <nphamcs@gmail.com>
Cc: Baoquan He <bhe@redhat.com>
Cc: Barry Song <baohua@kernel.org>
Cc: "Huang, Ying" <ying.huang@linux.alibaba.com>
Cc: Kemeng Shi <shikemeng@huaweicloud.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Chris Li
2025-08-12 00:10:58 -07:00
committed by Andrew Morton
parent 9d246d7410
commit 348e474f18
1 changed files with 47 additions and 39 deletions
Download Patch File Download Diff File Expand all files Collapse all files

86
mm/swapfile.c
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@@ -820,6 +820,29 @@ out:
return found;
}
static unsigned int alloc_swap_scan_list(struct swap_info_struct *si,
struct list_head *list,
unsigned int order,
unsigned char usage,
bool scan_all)
{
unsigned int found = SWAP_ENTRY_INVALID;
do {
struct swap_cluster_info *ci = isolate_lock_cluster(si, list);
unsigned long offset;
if (!ci)
break;
offset = cluster_offset(si, ci);
found = alloc_swap_scan_cluster(si, ci, offset, order, usage);
if (found)
break;
} while (scan_all);
return found;
}
static void swap_reclaim_full_clusters(struct swap_info_struct *si, bool force)
{
long to_scan = 1;
@@ -913,32 +936,24 @@ new_cluster:
* to spread out the writes.
*/
if (si->flags & SWP_PAGE_DISCARD) {
ci = isolate_lock_cluster(si, &si->free_clusters);
if (ci) {
found = alloc_swap_scan_cluster(si, ci, cluster_offset(si, ci),
order, usage);
if (found)
goto done;
}
found = alloc_swap_scan_list(si, &si->free_clusters, order, usage,
false);
if (found)
goto done;
}
if (order < PMD_ORDER) {
while ((ci = isolate_lock_cluster(si, &si->nonfull_clusters[order]))) {
found = alloc_swap_scan_cluster(si, ci, cluster_offset(si, ci),
order, usage);
if (found)
goto done;
}
found = alloc_swap_scan_list(si, &si->nonfull_clusters[order],
order, usage, true);
if (found)
goto done;
}
if (!(si->flags & SWP_PAGE_DISCARD)) {
ci = isolate_lock_cluster(si, &si->free_clusters);
if (ci) {
found = alloc_swap_scan_cluster(si, ci, cluster_offset(si, ci),
order, usage);
if (found)
goto done;
}
found = alloc_swap_scan_list(si, &si->free_clusters, order, usage,
false);
if (found)
goto done;
}
/* Try reclaim full clusters if free and nonfull lists are drained */
@@ -952,13 +967,10 @@ new_cluster:
* failure is not critical. Scanning one cluster still
* keeps the list rotated and reclaimed (for HAS_CACHE).
*/
ci = isolate_lock_cluster(si, &si->frag_clusters[order]);
if (ci) {
found = alloc_swap_scan_cluster(si, ci, cluster_offset(si, ci),
order, usage);
if (found)
goto done;
}
found = alloc_swap_scan_list(si, &si->frag_clusters[order], order,
usage, false);
if (found)
goto done;
}
/*
@@ -977,19 +989,15 @@ new_cluster:
* Clusters here have at least one usable slots and can't fail order 0
* allocation, but reclaim may drop si->lock and race with another user.
*/
while ((ci = isolate_lock_cluster(si, &si->frag_clusters[o]))) {
found = alloc_swap_scan_cluster(si, ci, cluster_offset(si, ci),
0, usage);
if (found)
goto done;
}
found = alloc_swap_scan_list(si, &si->frag_clusters[o],
0, usage, true);
if (found)
goto done;
while ((ci = isolate_lock_cluster(si, &si->nonfull_clusters[o]))) {
found = alloc_swap_scan_cluster(si, ci, cluster_offset(si, ci),
0, usage);
if (found)
goto done;
}
found = alloc_swap_scan_list(si, &si->nonfull_clusters[o],
0, usage, true);
if (found)
goto done;
}
done:
if (!(si->flags & SWP_SOLIDSTATE))