mm/truncate: batch-clear shadow entries

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

Also, rename clear_shadow_entry() to clear_shadow_entries() accordingly.

[yuzhao@google.com: v2]
Link: https://lkml.kernel.org/r/20240710060933.3979380-1-yuzhao@google.com
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>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/mm/truncate.c b/mm/truncate.c
index 5ce62a939e5541d98fee66060d162b26f245ffc0..dfb3d1f4d456e531eb4e1bd0fb9d2303d0211aab 100644 (file)
--- a/mm/truncate.c
+++ b/mm/truncate.c
@@ -39,12 +39,25 @@ static inline void __clear_shadow_entry(struct address_space *mapping,
        xas_store(&xas, NULL);
 }
 
-static void clear_shadow_entry(struct address_space *mapping, pgoff_t index,
-                              void *entry)
+static void clear_shadow_entries(struct address_space *mapping,
+                                struct folio_batch *fbatch, pgoff_t *indices)
 {
+       int i;
+
+       /* Handled by shmem itself, or for DAX we do nothing. */
+       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 +118,6 @@ static void truncate_folio_batch_exceptionals(struct address_space *mapping,
        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 +477,7 @@ unsigned long mapping_try_invalidate(struct address_space *mapping,
        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 +487,8 @@ unsigned long mapping_try_invalidate(struct address_space *mapping,
                        /* 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 +506,10 @@ unsigned long mapping_try_invalidate(struct address_space *mapping,
                        }
                        count += ret;
                }
+
+               if (xa_has_values)
+                       clear_shadow_entries(mapping, &fbatch, indices);
+
                folio_batch_remove_exceptionals(&fbatch);
                folio_batch_release(&fbatch);
                cond_resched();
@@ -616,6 +604,7 @@ int invalidate_inode_pages2_range(struct address_space *mapping,
        int ret = 0;
        int ret2 = 0;
        int did_range_unmap = 0;
+       bool xa_has_values = false;
 
        if (mapping_empty(mapping))
                return 0;
@@ -629,8 +618,9 @@ int invalidate_inode_pages2_range(struct address_space *mapping,
                        /* 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 +656,10 @@ int invalidate_inode_pages2_range(struct address_space *mapping,
                                ret = ret2;
                        folio_unlock(folio);
                }
+
+               if (xa_has_values)
+                       clear_shadow_entries(mapping, &fbatch, indices);
+
                folio_batch_remove_exceptionals(&fbatch);
                folio_batch_release(&fbatch);
                cond_resched();