The patch titled Subject: mm/truncate: batch-clear shadow entries has been added to the -mm mm-unstable branch. Its filename is mm-truncate-batch-clear-shadow-entries.patch

This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches...

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: Yu Zhao yuzhao@google.com Subject: mm/truncate: batch-clear shadow entries Date: Mon, 8 Jul 2024 15:27:53 -0600

Make clear_shadow_entry() clear shadow entries in `struct folio_batch` so that it can reduce contention on i_lock and i_pages locks, e.g.,

watchdog: BUG: soft lockup - CPU#29 stuck for 11s! [fio:2701649] clear_shadow_entry+0x3d/0x100 mapping_try_invalidate+0x117/0x1d0 invalidate_mapping_pages+0x10/0x20 invalidate_bdev+0x3c/0x50 blkdev_common_ioctl+0x5f7/0xa90 blkdev_ioctl+0x109/0x270

Link: https://lkml.kernel.org/r/20240708212753.3120511-1-yuzhao@google.com Reported-by: Bharata B Rao bharata@amd.com Closes: https://lore.kernel.org/d2841226-e27b-4d3d-a578-63587a3aa4f3@amd.com/ Signed-off-by: Yu Zhao yuzhao@google.com Cc: Mel Gorman mgorman@techsingularity.net Cc: Johannes Weiner hannes@cmpxchg.org Cc: stable@vger.kernel.org Signed-off-by: Andrew Morton akpm@linux-foundation.org ---

mm/truncate.c | 67 +++++++++++++++++++++--------------------------- 1 file changed, 30 insertions(+), 37 deletions(-)

--- a/mm/truncate.c~mm-truncate-batch-clear-shadow-entries +++ a/mm/truncate.c @@ -39,12 +39,24 @@ static inline void __clear_shadow_entry( xas_store(&xas, NULL); }

-static void clear_shadow_entry(struct address_space *mapping, pgoff_t index, - void *entry) +static void clear_shadow_entry(struct address_space *mapping, + struct folio_batch *fbatch, pgoff_t *indices) { + int i; + + if (shmem_mapping(mapping) || dax_mapping(mapping)) + return; + spin_lock(&mapping->host->i_lock); xa_lock_irq(&mapping->i_pages); - __clear_shadow_entry(mapping, index, entry); + + for (i = 0; i < folio_batch_count(fbatch); i++) { + struct folio *folio = fbatch->folios[i]; + + if (xa_is_value(folio)) + __clear_shadow_entry(mapping, indices[i], folio); + } + xa_unlock_irq(&mapping->i_pages); if (mapping_shrinkable(mapping)) inode_add_lru(mapping->host); @@ -105,36 +117,6 @@ static void truncate_folio_batch_excepti fbatch->nr = j; }

-/* - * Invalidate exceptional entry if easily possible. This handles exceptional - * entries for invalidate_inode_pages(). - */ -static int invalidate_exceptional_entry(struct address_space *mapping, - pgoff_t index, void *entry) -{ - /* Handled by shmem itself, or for DAX we do nothing. */ - if (shmem_mapping(mapping) || dax_mapping(mapping)) - return 1; - clear_shadow_entry(mapping, index, entry); - return 1; -} - -/* - * Invalidate exceptional entry if clean. This handles exceptional entries for - * invalidate_inode_pages2() so for DAX it evicts only clean entries. - */ -static int invalidate_exceptional_entry2(struct address_space *mapping, - pgoff_t index, void *entry) -{ - /* Handled by shmem itself */ - if (shmem_mapping(mapping)) - return 1; - if (dax_mapping(mapping)) - return dax_invalidate_mapping_entry_sync(mapping, index); - clear_shadow_entry(mapping, index, entry); - return 1; -} - /** * folio_invalidate - Invalidate part or all of a folio. * @folio: The folio which is affected. @@ -494,6 +476,7 @@ unsigned long mapping_try_invalidate(str unsigned long ret; unsigned long count = 0; int i; + bool xa_has_values = false;

folio_batch_init(&fbatch); while (find_lock_entries(mapping, &index, end, &fbatch, indices)) { @@ -503,8 +486,8 @@ unsigned long mapping_try_invalidate(str /* We rely upon deletion not changing folio->index */

if (xa_is_value(folio)) { - count += invalidate_exceptional_entry(mapping, - indices[i], folio); + xa_has_values = true; + count++; continue; }

@@ -522,6 +505,10 @@ unsigned long mapping_try_invalidate(str } count += ret; } + + if (xa_has_values) + clear_shadow_entry(mapping, &fbatch, indices); + folio_batch_remove_exceptionals(&fbatch); folio_batch_release(&fbatch); cond_resched(); @@ -616,6 +603,7 @@ int invalidate_inode_pages2_range(struct int ret = 0; int ret2 = 0; int did_range_unmap = 0; + bool xa_has_values = false;

if (mapping_empty(mapping)) return 0; @@ -629,8 +617,9 @@ int invalidate_inode_pages2_range(struct /* We rely upon deletion not changing folio->index */

if (xa_is_value(folio)) { - if (!invalidate_exceptional_entry2(mapping, - indices[i], folio)) + xa_has_values = true; + if (dax_mapping(mapping) && + !dax_invalidate_mapping_entry_sync(mapping, indices[i])) ret = -EBUSY; continue; } @@ -666,6 +655,10 @@ int invalidate_inode_pages2_range(struct ret = ret2; folio_unlock(folio); } + + if (xa_has_values) + clear_shadow_entry(mapping, &fbatch, indices); + folio_batch_remove_exceptionals(&fbatch); folio_batch_release(&fbatch); cond_resched(); _

Patches currently in -mm which might be from yuzhao@google.com are

mm-truncate-batch-clear-shadow-entries.patch