The patch titled
Subject: mm: shmem: support large folio swap out
has been added to the -mm mm-unstable branch. Its filename is
mm-shmem-support-large-folio-swap-out.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-shmem-support-large-folio-swap-out.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: Baolin Wang <baolin.wang@xxxxxxxxxxxxxxxxx>
Subject: mm: shmem: support large folio swap out
Date: Tue, 18 Jun 2024 14:54:21 +0800
Shmem will support large folio allocation [1] [2] to get a better
performance, however, the memory reclaim still splits the precious large
folios when trying to swap out shmem, which may lead to the memory
fragmentation issue and can not take advantage of the large folio for
shmeme.
Moreover, the swap code already supports for swapping out large folio
without split, hence this patch set supports the large folio swap out for
shmem.
Note the i915_gem_shmem driver still need to be split when swapping, thus
add a new flag 'split_large_folio' for writeback_control to indicate
spliting the large folio.
[1] https://lore.kernel.org/all/cover.1717495894.git.baolin.wang@xxxxxxxxxxxxxxxxx/
[2] https://lore.kernel.org/all/20240515055719.32577-1-da.gomez@xxxxxxxxxxx/
Link: https://lkml.kernel.org/r/df16cdc6c7ce9b3f8e4f71cc6005738c67b3dacf.1718690645.git.baolin.wang@xxxxxxxxxxxxxxxxx
Signed-off-by: Baolin Wang <baolin.wang@xxxxxxxxxxxxxxxxx>
Cc: Barry Song <21cnbao@xxxxxxxxx>
Cc: Chris Li <chrisl@xxxxxxxxxx>
Cc: David Hildenbrand <david@xxxxxxxxxx>
Cc: "Huang, Ying" <ying.huang@xxxxxxxxx>
Cc: Hugh Dickins <hughd@xxxxxxxxxx>
Cc: Kefeng Wang <wangkefeng.wang@xxxxxxxxxx>
Cc: Lance Yang <ioworker0@xxxxxxxxx>
Cc: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
Cc: Pankaj Raghav <p.raghav@xxxxxxxxxxx>
Cc: Ryan Roberts <ryan.roberts@xxxxxxx>
Cc: Yang Shi <shy828301@xxxxxxxxx>
Cc: Zi Yan <ziy@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
drivers/gpu/drm/i915/gem/i915_gem_shmem.c | 1 +
include/linux/writeback.h | 1 +
mm/shmem.c | 3 +--
mm/vmscan.c | 14 ++++++++++++--
4 files changed, 15 insertions(+), 4 deletions(-)
--- a/drivers/gpu/drm/i915/gem/i915_gem_shmem.c~mm-shmem-support-large-folio-swap-out
+++ a/drivers/gpu/drm/i915/gem/i915_gem_shmem.c
@@ -308,6 +308,7 @@ void __shmem_writeback(size_t size, stru
.range_start = 0,
.range_end = LLONG_MAX,
.for_reclaim = 1,
+ .split_large_folio = 1,
};
unsigned long i;
--- a/include/linux/writeback.h~mm-shmem-support-large-folio-swap-out
+++ a/include/linux/writeback.h
@@ -63,6 +63,7 @@ struct writeback_control {
unsigned range_cyclic:1; /* range_start is cyclic */
unsigned for_sync:1; /* sync(2) WB_SYNC_ALL writeback */
unsigned unpinned_netfs_wb:1; /* Cleared I_PINNING_NETFS_WB */
+ unsigned split_large_folio:1; /* Split large folio for shmem writeback */
/*
* When writeback IOs are bounced through async layers, only the
--- a/mm/shmem.c~mm-shmem-support-large-folio-swap-out
+++ a/mm/shmem.c
@@ -775,7 +775,6 @@ static int shmem_add_to_page_cache(struc
VM_BUG_ON_FOLIO(index != round_down(index, nr), folio);
VM_BUG_ON_FOLIO(!folio_test_locked(folio), folio);
VM_BUG_ON_FOLIO(!folio_test_swapbacked(folio), folio);
- VM_BUG_ON(expected && folio_test_large(folio));
folio_ref_add(folio, nr);
folio->mapping = mapping;
@@ -1462,7 +1461,7 @@ static int shmem_writepage(struct page *
* "force", drivers/gpu/drm/i915/gem/i915_gem_shmem.c gets huge pages,
* and its shmem_writeback() needs them to be split when swapping.
*/
- if (folio_test_large(folio)) {
+ if (wbc->split_large_folio && folio_test_large(folio)) {
/* Ensure the subpages are still dirty */
folio_test_set_dirty(folio);
if (split_huge_page(page) < 0)
--- a/mm/vmscan.c~mm-shmem-support-large-folio-swap-out
+++ a/mm/vmscan.c
@@ -1245,8 +1245,12 @@ retry:
if (!total_swap_pages)
goto activate_locked;
- /* Split shmem folio */
- if (split_folio_to_list(folio, folio_list))
+ /*
+ * Only split shmem folio when CONFIG_THP_SWAP
+ * is not enabled.
+ */
+ if (!IS_ENABLED(CONFIG_THP_SWAP) &&
+ split_folio_to_list(folio, folio_list))
goto keep_locked;
}
@@ -1348,10 +1352,16 @@ retry:
* starts and then write it out here.
*/
try_to_unmap_flush_dirty();
+try_pageout:
switch (pageout(folio, mapping, &plug)) {
case PAGE_KEEP:
goto keep_locked;
case PAGE_ACTIVATE:
+ if (shmem_mapping(mapping) && folio_test_large(folio) &&
+ !split_folio_to_list(folio, folio_list)) {
+ nr_pages = 1;
+ goto try_pageout;
+ }
goto activate_locked;
case PAGE_SUCCESS:
stat->nr_pageout += nr_pages;
_
Patches currently in -mm which might be from baolin.wang@xxxxxxxxxxxxxxxxx are
mm-memory-extend-finish_fault-to-support-large-folio.patch
mm-memory-extend-finish_fault-to-support-large-folio-fix.patch
mm-memory-extend-finish_fault-to-support-large-folio-fix-fix.patch
mm-shmem-add-thp-validation-for-pmd-mapped-thp-related-statistics.patch
mm-shmem-add-multi-size-thp-sysfs-interface-for-anonymous-shmem.patch
mm-shmem-add-multi-size-thp-sysfs-interface-for-anonymous-shmem-fix.patch
mm-shmem-add-multi-size-thp-sysfs-interface-for-anonymous-shmem-fix-3.patch
mm-shmem-add-mthp-support-for-anonymous-shmem.patch
mm-shmem-add-mthp-size-alignment-in-shmem_get_unmapped_area.patch
mm-shmem-add-mthp-counters-for-anonymous-shmem.patch
mm-shmem-add-mthp-counters-for-anonymous-shmem-fix.patch
mm-memcontrol-add-vm_bug_on_folio-to-catch-lru-folio-in-mem_cgroup_migrate.patch
mm-vmscan-add-validation-before-spliting-shmem-large-folio.patch
mm-swap-extend-swap_shmem_alloc-to-support-batch-swap_map_shmem-flag-setting.patch
mm-shmem-extend-shmem_partial_swap_usage-to-support-large-folio-swap.patch
mm-filemap-use-xa_get_order-to-get-the-swap-entry-order.patch
mm-shmem-use-swap_free_nr-to-free-shmem-swap-entries.patch
mm-shmem-support-large-folio-allocation-for-shmem_replace_folio.patch
mm-shmem-drop-folio-reference-count-using-nr_pages-in-shmem_delete_from_page_cache.patch
mm-shmem-support-large-folio-swap-out.patch
