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From: Andrew Morton <akpm@linux-foundation.org>
To: aarcange@redhat.com, mike.kravetz@oracle.com,
	mm-commits@vger.kernel.org, peterx@redhat.com,
	stable@vger.kernel.org, willy@infradead.org
Subject: + mm-hugetlb-fix-calculation-of-adjust_range_if_pmd_sharing_possible.patch added to -mm tree
Date: Fri, 31 Jul 2020 13:57:10 -0700
Message-ID: <20200731205710.iB3KouoTG%akpm@linux-foundation.org> (raw)
In-Reply-To: <20200723211432.b31831a0df3bc2cbdae31b40@linux-foundation.org>


The patch titled
     Subject: mm/hugetlb: fix calculation of adjust_range_if_pmd_sharing_possible
has been added to the -mm tree.  Its filename is
     mm-hugetlb-fix-calculation-of-adjust_range_if_pmd_sharing_possible.patch

This patch should soon appear at
    http://ozlabs.org/~akpm/mmots/broken-out/mm-hugetlb-fix-calculation-of-adjust_range_if_pmd_sharing_possible.patch
and later at
    http://ozlabs.org/~akpm/mmotm/broken-out/mm-hugetlb-fix-calculation-of-adjust_range_if_pmd_sharing_possible.patch

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*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***

The -mm tree is included into linux-next and is updated
there every 3-4 working days

------------------------------------------------------
From: Peter Xu <peterx@redhat.com>
Subject: mm/hugetlb: fix calculation of adjust_range_if_pmd_sharing_possible

This is found by code observation only.

Firstly, the worst case scenario should assume the whole range was covered
by pmd sharing.  The old algorithm might not work as expected for ranges
like (1g-2m, 1g+2m), where the adjusted range should be (0, 1g+2m) but the
expected range should be (0, 2g).

Since at it, remove the loop since it should not be required.  With that,
the new code should be faster too when the invalidating range is huge.

Mike said:

: With range (1g-2m, 1g+2m) within a vma (0, 2g) the existing code will only
: adjust to (0, 1g+2m) which is incorrect.
: 
: We should cc stable.  The original reason for adjusting the range was to
: prevent data corruption (getting wrong page).  Since the range is not
: always adjusted correctly, the potential for corruption still exists.
: 
: However, I am fairly confident that adjust_range_if_pmd_sharing_possible
: is only gong to be called in two cases:
: 
: 1) for a single page
: 2) for range == entire vma
: 
: In those cases, the current code should produce the correct results.
: 
: To be safe, let's just cc stable.

Link: http://lkml.kernel.org/r/20200730201636.74778-1-peterx@redhat.com
Fixes: 017b1660df89 ("mm: migration: fix migration of huge PMD shared pages")
Signed-off-by: Peter Xu <peterx@redhat.com>
Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/hugetlb.c |   24 ++++++++++--------------
 1 file changed, 10 insertions(+), 14 deletions(-)

--- a/mm/hugetlb.c~mm-hugetlb-fix-calculation-of-adjust_range_if_pmd_sharing_possible
+++ a/mm/hugetlb.c
@@ -5314,25 +5314,21 @@ static bool vma_shareable(struct vm_area
 void adjust_range_if_pmd_sharing_possible(struct vm_area_struct *vma,
 				unsigned long *start, unsigned long *end)
 {
-	unsigned long check_addr;
+	unsigned long a_start, a_end;
 
 	if (!(vma->vm_flags & VM_MAYSHARE))
 		return;
 
-	for (check_addr = *start; check_addr < *end; check_addr += PUD_SIZE) {
-		unsigned long a_start = check_addr & PUD_MASK;
-		unsigned long a_end = a_start + PUD_SIZE;
+	/* Extend the range to be PUD aligned for a worst case scenario */
+	a_start = ALIGN_DOWN(*start, PUD_SIZE);
+	a_end = ALIGN(*end, PUD_SIZE);
 
-		/*
-		 * If sharing is possible, adjust start/end if necessary.
-		 */
-		if (range_in_vma(vma, a_start, a_end)) {
-			if (a_start < *start)
-				*start = a_start;
-			if (a_end > *end)
-				*end = a_end;
-		}
-	}
+	/*
+	 * Intersect the range with the vma range, since pmd sharing won't be
+	 * across vma after all
+	 */
+	*start = max(vma->vm_start, a_start);
+	*end = min(vma->vm_end, a_end);
 }
 
 /*
_

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

mm-hugetlb-fix-calculation-of-adjust_range_if_pmd_sharing_possible.patch
mm-do-page-fault-accounting-in-handle_mm_fault.patch
mm-alpha-use-general-page-fault-accounting.patch
mm-arc-use-general-page-fault-accounting.patch
mm-arm-use-general-page-fault-accounting.patch
mm-arm64-use-general-page-fault-accounting.patch
mm-csky-use-general-page-fault-accounting.patch
mm-hexagon-use-general-page-fault-accounting.patch
mm-ia64-use-general-page-fault-accounting.patch
mm-m68k-use-general-page-fault-accounting.patch
mm-microblaze-use-general-page-fault-accounting.patch
mm-mips-use-general-page-fault-accounting.patch
mm-nds32-use-general-page-fault-accounting.patch
mm-nios2-use-general-page-fault-accounting.patch
mm-openrisc-use-general-page-fault-accounting.patch
mm-parisc-use-general-page-fault-accounting.patch
mm-powerpc-use-general-page-fault-accounting.patch
mm-riscv-use-general-page-fault-accounting.patch
mm-s390-use-general-page-fault-accounting.patch
mm-sh-use-general-page-fault-accounting.patch
mm-sparc32-use-general-page-fault-accounting.patch
mm-sparc64-use-general-page-fault-accounting.patch
mm-x86-use-general-page-fault-accounting.patch
mm-xtensa-use-general-page-fault-accounting.patch
mm-clean-up-the-last-pieces-of-page-fault-accountings.patch
mm-gup-remove-task_struct-pointer-for-all-gup-code.patch


  parent reply index

Thread overview: 86+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-07-24  4:14 incoming Andrew Morton
2020-07-24  4:15 ` [patch 01/15] mm/memory.c: avoid access flag update TLB flush for retried page fault Andrew Morton
     [not found]   ` <30cf7356-bef1-c621-60cb-e12a8bd9111d@linux.alibaba.com>
2020-07-24  4:56     ` Andrew Morton
2020-07-24  4:15 ` [patch 02/15] mm/mmap.c: close race between munmap() and expand_upwards()/downwards() Andrew Morton
2020-07-24  4:15 ` [patch 03/15] vfs/xattr: mm/shmem: kernfs: release simple xattr entry in a right way Andrew Morton
2020-07-24  4:15 ` [patch 04/15] mm: initialize return of vm_insert_pages Andrew Morton
2020-07-24  4:15 ` [patch 05/15] mm/memcontrol: fix OOPS inside mem_cgroup_get_nr_swap_pages() Andrew Morton
2020-07-24  4:15 ` [patch 06/15] mm/memcg: fix refcount error while moving and swapping Andrew Morton
2020-07-24  4:15 ` [patch 07/15] mm: memcg/slab: fix memory leak at non-root kmem_cache destroy Andrew Morton
2020-07-24  4:15 ` [patch 08/15] mm/hugetlb: avoid hardcoding while checking if cma is enabled Andrew Morton
2020-07-24  4:15 ` [patch 09/15] khugepaged: fix null-pointer dereference due to race Andrew Morton
2020-07-24  4:15 ` [patch 10/15] mailmap: add entry for Mike Rapoport Andrew Morton
2020-07-24  4:15 ` [patch 11/15] squashfs: fix length field overlap check in metadata reading Andrew Morton
2020-07-24  4:15 ` [patch 12/15] scripts/decode_stacktrace: strip basepath from all paths Andrew Morton
2020-07-24  4:15 ` [patch 13/15] io-mapping: indicate mapping failure Andrew Morton
2020-07-24  4:15 ` [patch 14/15] MAINTAINERS: add KCOV section Andrew Morton
2020-07-24  4:15 ` [patch 15/15] scripts/gdb: fix lx-symbols 'gdb.error' while loading modules Andrew Morton
2020-07-27 19:47 ` + mm-remove-unnecessary-wrapper-function-do_mmap_pgoff.patch added to -mm tree Andrew Morton
2020-07-27 19:56 ` + nilfs2-only-call-unlock_new_inode-if-i_new.patch " Andrew Morton
2020-07-27 19:57 ` + nilfs2-convert-__nilfs_msg-to-integrate-the-level-and-format.patch " Andrew Morton
2020-07-27 19:57 ` + nilfs2-use-a-more-common-logging-style.patch " Andrew Morton
2020-07-27 19:58 ` + checkpatch-add-test-for-repeated-words.patch " Andrew Morton
2020-07-27 20:05 ` + ocfs2-replace-http-links-with-https-ones.patch " Andrew Morton
2020-07-27 20:09 ` + ocfs2-fix-unbalanced-locking.patch " Andrew Morton
2020-07-27 20:10 ` + kernelh-remove-duplicate-include-of-asm-div64h.patch " Andrew Morton
2020-07-27 20:11 ` + tools-replace-http-links-with-https-ones.patch " Andrew Morton
2020-07-27 20:12 ` + lib-replace-http-links-with-https-ones.patch " Andrew Morton
2020-07-27 20:12 ` + include-replace-http-links-with-https-ones.patch " Andrew Morton
2020-07-27 20:34 ` + mm-make-mm-locked_vm-an-atomic64-counter.patch " Andrew Morton
2020-07-27 20:34 ` + mm-util-account_locked_vm-does-not-hold-mmap_lock.patch " Andrew Morton
2020-07-27 20:37 ` + cg_read_strcmp-fix-null-pointer-dereference.patch " Andrew Morton
2020-07-27 20:51 ` + mm-hugetlb-add-mempolicy-check-in-the-reservation-routine.patch " Andrew Morton
2020-07-27 20:52 ` [withdrawn] checkpatch-support-deprecated-terms-checking.patch removed from " Andrew Morton
2020-07-27 23:47 ` [obsolete] scripts-deprecated_terms-recommend-denylist-allowlist-instead-of-blacklist-whitelist.patch " Andrew Morton
2020-07-27 23:50 ` [obsolete] scripts-deprecated_terms-sync-with-inclusive-terms.patch " Andrew Morton
2020-07-28  0:18 ` [failures] mm-hugetlb-add-mempolicy-check-in-the-reservation-routine.patch " Andrew Morton
2020-07-28  1:19 ` mmotm 2020-07-27-18-18 uploaded Andrew Morton
     [not found]   ` <ae87385b-f830-dbdf-ebc7-1afb82a7fed0@infradead.org>
2020-07-28 21:55     ` mmotm 2020-07-27-18-18 uploaded (mm/page_alloc.c) Andrew Morton
     [not found]       ` <20200729082053.6c2fb654@canb.auug.org.au>
2020-07-28 22:31         ` Andrew Morton
     [not found]       ` <048cef07-ad4b-8788-94a4-e144de731ab6@infradead.org>
2020-07-29  1:44         ` Andrew Morton
2020-07-28 20:53 ` + mm-mempolicy-fix-kerneldoc-of-numa_map_to_online_node.patch added to -mm tree Andrew Morton
2020-07-28 20:53 ` + mm-mmu_notifier-fix-and-extend-kerneldoc.patch " Andrew Morton
2020-07-28 20:54 ` + mm-swap-fix-kerneldoc-of-swap_vma_readahead.patch " Andrew Morton
2020-07-28 20:58 ` + mm-memcontrol-dont-count-limit-setting-reclaim-as-memory-pressure.patch " Andrew Morton
2020-07-28 21:01 ` + mm-memcontrol-restore-proper-dirty-throttling-when-memoryhigh-changes.patch " Andrew Morton
2020-07-28 22:06 ` + mm-compaction-correct-the-comments-of-compact_defer_shift.patch " Andrew Morton
2020-07-28 22:09 ` + selftests-add-mincore-tests.patch " Andrew Morton
2020-07-28 22:16 ` + proc-pid-smaps-consistent-whitespace-output-format.patch " Andrew Morton
2020-07-28 22:21 ` + xtensa-switch-to-generic-version-of-pte-allocation-fix.patch " Andrew Morton
2020-07-28 22:21 ` Andrew Morton
2020-07-29 21:49 ` + mm-slab-avoid-the-use-of-one-element-array-and-use-struct_size-helper.patch " Andrew Morton
2020-07-29 23:52 ` [obsolete] mm-slab-avoid-the-use-of-one-element-array-and-use-struct_size-helper.patch removed from " Andrew Morton
2020-07-31 19:24 ` + kasan-dont-tag-stacks-allocated-with-pagealloc.patch added to " Andrew Morton
2020-07-31 19:24 ` + kasan-arm64-dont-instrument-functions-that-enable-kasan.patch " Andrew Morton
2020-07-31 19:24 ` + kasan-allow-enabling-stack-tagging-for-tag-based-mode.patch " Andrew Morton
2020-07-31 19:24 ` + kasan-adjust-kasan_stack_oob-for-tag-based-mode.patch " Andrew Morton
2020-07-31 20:00 ` [obsolete] mmhwpoison-rework-soft-offline-for-in-use-pages-fix.patch removed from " Andrew Morton
2020-07-31 20:05 ` + mmhwpoison-cleanup-unused-pagehuge-check.patch added to " Andrew Morton
2020-07-31 20:05 ` + mm-hwpoison-remove-recalculating-hpage.patch " Andrew Morton
2020-07-31 20:05 ` + mmmadvise-call-soft_offline_page-without-mf_count_increased.patch " Andrew Morton
2020-07-31 20:05 ` + mmmadvise-refactor-madvise_inject_error.patch " Andrew Morton
2020-07-31 20:05 ` + mmhwpoison-inject-dont-pin-for-hwpoison_filter.patch " Andrew Morton
2020-07-31 20:05 ` + mmhwpoison-un-export-get_hwpoison_page-and-make-it-static.patch " Andrew Morton
2020-07-31 20:05 ` + mmhwpoison-kill-put_hwpoison_page.patch " Andrew Morton
2020-07-31 20:06 ` + mmhwpoison-remove-mf_count_increased.patch " Andrew Morton
2020-07-31 20:06 ` + mmhwpoison-remove-flag-argument-from-soft-offline-functions.patch " Andrew Morton
2020-07-31 20:06 ` + mmhwpoison-unify-thp-handling-for-hard-and-soft-offline.patch " Andrew Morton
2020-07-31 20:06 ` + mmhwpoison-rework-soft-offline-for-free-pages.patch " Andrew Morton
2020-07-31 20:06 ` + mmhwpoison-rework-soft-offline-for-in-use-pages.patch " Andrew Morton
2020-07-31 20:06 ` + mmhwpoison-refactor-soft_offline_huge_page-and-__soft_offline_page.patch " Andrew Morton
2020-07-31 20:06 ` + mmhwpoison-return-0-if-the-page-is-already-poisoned-in-soft-offline.patch " Andrew Morton
2020-07-31 20:06 ` + mmhwpoison-introduce-mf_msg_unsplit_thp.patch " Andrew Morton
2020-07-31 20:06 ` + mmhwpoison-double-check-page-count-in-__get_any_page.patch " Andrew Morton
2020-07-31 20:23 ` + mm-gup-restrict-cma-region-by-using-allocation-scope-api.patch " Andrew Morton
2020-07-31 20:23 ` + mm-hugetlb-make-hugetlb-migration-callback-cma-aware.patch " Andrew Morton
2020-07-31 20:23 ` + mm-gup-use-a-standard-migration-target-allocation-callback.patch " Andrew Morton
2020-07-31 20:25 ` + mm-migrate-make-a-standard-migration-target-allocation-function-fix.patch " Andrew Morton
2020-07-31 20:26 ` + mm-memcontrol-decouple-reference-counting-from-page-accounting-fix.patch " Andrew Morton
2020-07-31 20:32 ` + mm-dmapoolc-add-warn_on-in-dma_pool_destroy.patch " Andrew Morton
2020-07-31 20:49 ` + kstrto-correct-documentation-references-to-simple_strto.patch " Andrew Morton
2020-07-31 20:49 ` + kstrto-do-not-describe-simple_strto-as-obsolete-replaced.patch " Andrew Morton
2020-07-31 20:57 ` Andrew Morton [this message]
2020-07-31 20:59 ` + poison-remove-obsolete-comment.patch " Andrew Morton
2020-07-31 21:02 ` + cma-dont-quit-at-first-error-when-activating-reserved-areas.patch " Andrew Morton
2020-07-31 21:10 ` [nacked] mm-dmapoolc-add-warn_on-in-dma_pool_destroy.patch removed from " Andrew Morton
2020-07-31 23:46 ` mmotm 2020-07-31-16-45 uploaded Andrew Morton

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