+ mm-huge_memory-remove-stale-locking-logic-from-__split_huge_pmd.patch added to -mm tree

* + mm-huge_memory-remove-stale-locking-logic-from-__split_huge_pmd.patch added to -mm tree
@ 2022-03-07 23:45 Andrew Morton
  0 siblings, 0 replies; 2+ messages in thread
From: Andrew Morton @ 2022-03-07 23:45 UTC (permalink / raw)
  To: mm-commits, zhangliang5, willy, vbabka, shy828301, shakeelb,
	rppt, roman.gushchin, rientjes, riel, peterx, oleg, nadav.amit,
	mike.kravetz, mhocko, kirill.shutemov, jhubbard, jgg, jannh,
	jack, hughd, hch, ddutile, aarcange, david, akpm


The patch titled
     Subject: mm/huge_memory: remove stale locking logic from __split_huge_pmd()
has been added to the -mm tree.  Its filename is
     mm-huge_memory-remove-stale-locking-logic-from-__split_huge_pmd.patch

This patch should soon appear at
    https://ozlabs.org/~akpm/mmots/broken-out/mm-huge_memory-remove-stale-locking-logic-from-__split_huge_pmd.patch
and later at
    https://ozlabs.org/~akpm/mmotm/broken-out/mm-huge_memory-remove-stale-locking-logic-from-__split_huge_pmd.patch

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------------------------------------------------------
From: David Hildenbrand <david@redhat.com>
Subject: mm/huge_memory: remove stale locking logic from __split_huge_pmd()

Let's remove the stale logic that was required for reuse_swap_page().

Link: https://lkml.kernel.org/r/20220131162940.210846-10-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: David Rientjes <rientjes@google.com>
Cc: Don Dutile <ddutile@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Jann Horn <jannh@google.com>
Cc: Jason Gunthorpe <jgg@nvidia.com>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Liang Zhang <zhangliang5@huawei.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Mike Rapoport <rppt@linux.ibm.com>
Cc: Nadav Amit <nadav.amit@gmail.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Rik van Riel <riel@surriel.com>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Yang Shi <shy828301@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/huge_memory.c |   32 +-------------------------------
 1 file changed, 1 insertion(+), 31 deletions(-)

--- a/mm/huge_memory.c~mm-huge_memory-remove-stale-locking-logic-from-__split_huge_pmd
+++ a/mm/huge_memory.c
@@ -2133,8 +2133,6 @@ void __split_huge_pmd(struct vm_area_str
 {
 	spinlock_t *ptl;
 	struct mmu_notifier_range range;
-	bool do_unlock_folio = false;
-	pmd_t _pmd;
 
 	mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma, vma->vm_mm,
 				address & HPAGE_PMD_MASK,
@@ -2153,42 +2151,14 @@ void __split_huge_pmd(struct vm_area_str
 			goto out;
 	}
 
-repeat:
 	if (pmd_trans_huge(*pmd)) {
-		if (!folio) {
+		if (!folio)
 			folio = page_folio(pmd_page(*pmd));
-			/*
-			 * An anonymous page must be locked, to ensure that a
-			 * concurrent reuse_swap_page() sees stable mapcount;
-			 * but reuse_swap_page() is not used on shmem or file,
-			 * and page lock must not be taken when zap_pmd_range()
-			 * calls __split_huge_pmd() while i_mmap_lock is held.
-			 */
-			if (folio_test_anon(folio)) {
-				if (unlikely(!folio_trylock(folio))) {
-					folio_get(folio);
-					_pmd = *pmd;
-					spin_unlock(ptl);
-					folio_lock(folio);
-					spin_lock(ptl);
-					if (unlikely(!pmd_same(*pmd, _pmd))) {
-						folio_unlock(folio);
-						folio_put(folio);
-						folio = NULL;
-						goto repeat;
-					}
-					folio_put(folio);
-				}
-				do_unlock_folio = true;
-			}
-		}
 	} else if (!(pmd_devmap(*pmd) || is_pmd_migration_entry(*pmd)))
 		goto out;
 	__split_huge_pmd_locked(vma, pmd, range.start, freeze);
 out:
 	spin_unlock(ptl);
-	if (do_unlock_folio)
-		folio_unlock(folio);
 	/*
 	 * No need to double call mmu_notifier->invalidate_range() callback.
 	 * They are 3 cases to consider inside __split_huge_pmd_locked():
_

Patches currently in -mm which might be from david@redhat.com are

cma-factor-out-minimum-alignment-requirement.patch
mm-enforce-pageblock_order-max_order.patch
drivers-base-memory-add-memory-block-to-memory-group-after-registration-succeeded.patch
drivers-base-node-consolidate-node-device-subsystem-initialization-in-node_dev_init.patch
drivers-base-node-rename-link_mem_sections-to-register_memory_block_under_node.patch
drivers-base-memory-determine-and-store-zone-for-single-zone-memory-blocks.patch
drivers-base-memory-clarify-adding-and-removing-of-memory-blocks.patch
proc-vmcore-fix-possible-deadlock-on-concurrent-mmap-and-read.patch
mm-optimize-do_wp_page-for-exclusive-pages-in-the-swapcache.patch
mm-optimize-do_wp_page-for-fresh-pages-in-local-lru-pagevecs.patch
mm-slightly-clarify-ksm-logic-in-do_swap_page.patch
mm-streamline-cow-logic-in-do_swap_page.patch
mm-huge_memory-streamline-cow-logic-in-do_huge_pmd_wp_page.patch
mm-khugepaged-remove-reuse_swap_page-usage.patch
mm-swapfile-remove-stale-reuse_swap_page.patch
mm-huge_memory-remove-stale-page_trans_huge_mapcount.patch
mm-huge_memory-remove-stale-locking-logic-from-__split_huge_pmd.patch


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