The patch titled
Subject: mm: shmem: support large folio swap out fix 2
has been added to the -mm mm-unstable branch. Its filename is
mm-shmem-support-large-folio-swap-out-fix-2.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-fix-2.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 fix 2
Date: Wed, 28 Aug 2024 16:28:38 +0800
As Hugh said:
"
The i915 THP splitting inshmem_writepage() was to avoid mm VM_BUG_ONs and
crashes when shmem.c did not support huge page swapout: but now you are
enabling that support, and such VM_BUG_ONs and crashes are gone (so far
as I can see: and this is written on a laptop using the i915 driver).
I cannot think of why i915 itself would care how mm implements swapout
(beyond enjoying faster): I think all the wbc->split_large_folio you
introduce here should be reverted.
"
So this fixup patch will remove the wbc->split_large_folio as suggested
by Hugh.
Link: https://lkml.kernel.org/r/1236a002daa301b3b9ba73d6c0fab348427cf295.1724833399.git.baolin.wang@xxxxxxxxxxxxxxxxx
Signed-off-by: Baolin Wang <baolin.wang@xxxxxxxxxxxxxxxxx>
Cc: Barry Song <baohua@xxxxxxxxxx>
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 <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 | 9 ++++-----
mm/vmscan.c | 4 +---
4 files changed, 5 insertions(+), 10 deletions(-)
--- a/drivers/gpu/drm/i915/gem/i915_gem_shmem.c~mm-shmem-support-large-folio-swap-out-fix-2
+++ a/drivers/gpu/drm/i915/gem/i915_gem_shmem.c
@@ -308,7 +308,6 @@ 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-fix-2
+++ a/include/linux/writeback.h
@@ -63,7 +63,6 @@ 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-fix-2
+++ a/mm/shmem.c
@@ -1478,19 +1478,18 @@ static int shmem_writepage(struct page *
goto redirty;
/*
- * If /sys/kernel/mm/transparent_hugepage/shmem_enabled is "always" or
- * "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 CONFIG_THP_SWAP is not enabled, the large folio should be
+ * split when swapping.
*
* And shrinkage of pages beyond i_size does not split swap, so
* swapout of a large folio crossing i_size needs to split too
* (unless fallocate has been used to preallocate beyond EOF).
*/
if (folio_test_large(folio)) {
- split = wbc->split_large_folio;
index = shmem_fallocend(inode,
DIV_ROUND_UP(i_size_read(inode), PAGE_SIZE));
- if (index > folio->index && index < folio_next_index(folio))
+ if ((index > folio->index && index < folio_next_index(folio)) ||
+ !IS_ENABLED(CONFIG_THP_SWAP))
split = true;
}
--- a/mm/vmscan.c~mm-shmem-support-large-folio-swap-out-fix-2
+++ a/mm/vmscan.c
@@ -681,10 +681,8 @@ static pageout_t pageout(struct folio *f
* not enabled or contiguous swap entries are failed to
* allocate.
*/
- if (shmem_mapping(mapping) && folio_test_large(folio)) {
+ if (shmem_mapping(mapping) && folio_test_large(folio))
wbc.list = folio_list;
- wbc.split_large_folio = !IS_ENABLED(CONFIG_THP_SWAP);
- }
folio_set_reclaim(folio);
res = mapping->a_ops->writepage(&folio->page, &wbc);
_
Patches currently in -mm which might be from baolin.wang@xxxxxxxxxxxxxxxxx are
mm-shmem-simplify-the-suitable-huge-orders-validation-for-tmpfs.patch
mm-shmem-rename-shmem_is_huge-to-shmem_huge_global_enabled.patch
mm-shmem-move-shmem_huge_global_enabled-into-shmem_allowable_huge_orders.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-support-large-folio-allocation-for-shmem_replace_folio-fix.patch
mm-shmem-support-large-folio-allocation-for-shmem_replace_folio-fix-fix.patch
mm-shmem-drop-folio-reference-count-using-nr_pages-in-shmem_delete_from_page_cache.patch
mm-shmem-split-large-entry-if-the-swapin-folio-is-not-large.patch
mm-shmem-split-large-entry-if-the-swapin-folio-is-not-large-fix-2.patch
mm-shmem-support-large-folio-swap-out.patch
mm-shmem-support-large-folio-swap-out-fix-2.patch
mm-khugepaged-expand-the-is_refcount_suitable-to-support-file-folios.patch
mm-khugepaged-use-the-number-of-pages-in-the-folio-to-check-the-reference-count.patch
mm-khugepaged-support-shmem-mthp-copy.patch
mm-khugepaged-support-shmem-mthp-collapse.patch
selftests-mm-support-shmem-mthp-collapse-testing.patch
