The patch titled
Subject: Revert "mm: skip CMA pages when they are not available"
has been added to the -mm mm-hotfixes-unstable branch. Its filename is
revert-mm-skip-cma-pages-when-they-are-not-available.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/revert-mm-skip-cma-pages-when-they-are-not-available.patch
This patch will later appear in the mm-hotfixes-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: Usama Arif <usamaarif642@xxxxxxxxx>
Subject: Revert "mm: skip CMA pages when they are not available"
Date: Wed, 21 Aug 2024 20:26:07 +0100
This reverts commit 5da226dbfce3a2f44978c2c7cf88166e69a6788b.
lruvec->lru_lock is highly contended and is held when calling
isolate_lru_folios. If the lru has a large number of CMA folios
consecutively, while the allocation type requested is not MIGRATE_MOVABLE,
isolate_lru_folios can hold the lock for a very long time while it skips
those. For FIO workload, ~150million order=0 folios were skipped to
isolate a few ZONE_DMA folios [1]. This can cause lockups [1] and high
memory pressure for extended periods of time [2].
[1] https://lore.kernel.org/all/CAOUHufbkhMZYz20aM_3rHZ3OcK4m2puji2FGpUpn_-DevGk3Kg@xxxxxxxxxxxxxx/
[2] https://lore.kernel.org/all/ZrssOrcJIDy8hacI@xxxxxxxxx/
Link: https://lkml.kernel.org/r/9060a32d-b2d7-48c0-8626-1db535653c54@xxxxxxxxx
Fixes: 5da226dbfce3 ("mm: skip CMA pages when they are not available")
Signed-off-by: Usama Arif <usamaarif642@xxxxxxxxx>
Cc: Bharata B Rao <bharata@xxxxxxx>
Cc: Breno Leitao <leitao@xxxxxxxxxx>
Cc: David Hildenbrand <david@xxxxxxxxxx>
Cc: Johannes Weiner <hannes@xxxxxxxxxxx>
Cc: Matthew Wilcox <willy@xxxxxxxxxxxxx>
Cc: Rik van Riel <riel@xxxxxxxxxxx>
Cc: Vlastimil Babka <vbabka@xxxxxxx>
Cc: Yu Zhao <yuzhao@xxxxxxxxxx>
Cc: Zhaoyang Huang <huangzhaoyang@xxxxxxxxx>
Cc: Zhaoyang Huang <zhaoyang.huang@xxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/vmscan.c | 41 ++++++++++++++++++++---------------------
1 file changed, 20 insertions(+), 21 deletions(-)
--- a/mm/vmscan.c~revert-mm-skip-cma-pages-when-they-are-not-available
+++ a/mm/vmscan.c
@@ -1604,25 +1604,6 @@ static __always_inline void update_lru_s
}
-#ifdef CONFIG_CMA
-/*
- * It is waste of effort to scan and reclaim CMA pages if it is not available
- * for current allocation context. Kswapd can not be enrolled as it can not
- * distinguish this scenario by using sc->gfp_mask = GFP_KERNEL
- */
-static bool skip_cma(struct folio *folio, struct scan_control *sc)
-{
- return !current_is_kswapd() &&
- gfp_migratetype(sc->gfp_mask) != MIGRATE_MOVABLE &&
- folio_migratetype(folio) == MIGRATE_CMA;
-}
-#else
-static bool skip_cma(struct folio *folio, struct scan_control *sc)
-{
- return false;
-}
-#endif
-
/*
* Isolating page from the lruvec to fill in @dst list by nr_to_scan times.
*
@@ -1669,8 +1650,7 @@ static unsigned long isolate_lru_folios(
nr_pages = folio_nr_pages(folio);
total_scan += nr_pages;
- if (folio_zonenum(folio) > sc->reclaim_idx ||
- skip_cma(folio, sc)) {
+ if (folio_zonenum(folio) > sc->reclaim_idx) {
nr_skipped[folio_zonenum(folio)] += nr_pages;
move_to = &folios_skipped;
goto move;
@@ -4273,6 +4253,25 @@ void lru_gen_soft_reclaim(struct mem_cgr
#endif /* CONFIG_MEMCG */
+#ifdef CONFIG_CMA
+/*
+ * It is waste of effort to scan and reclaim CMA pages if it is not available
+ * for current allocation context. Kswapd can not be enrolled as it can not
+ * distinguish this scenario by using sc->gfp_mask = GFP_KERNEL
+ */
+static bool skip_cma(struct folio *folio, struct scan_control *sc)
+{
+ return !current_is_kswapd() &&
+ gfp_migratetype(sc->gfp_mask) != MIGRATE_MOVABLE &&
+ folio_migratetype(folio) == MIGRATE_CMA;
+}
+#else
+static bool skip_cma(struct folio *folio, struct scan_control *sc)
+{
+ return false;
+}
+#endif
+
/******************************************************************************
* the eviction
******************************************************************************/
_
Patches currently in -mm which might be from usamaarif642@xxxxxxxxx are
revert-mm-skip-cma-pages-when-they-are-not-available.patch
