The patch titled
Subject: mm/damon/vaddr: safely walk page table
has been removed from the -mm tree. Its filename was
mm-damon-implement-primitives-for-the-virtual-memory-address-spaces-fix-3.patch
This patch was dropped because it was folded into mm-damon-implement-primitives-for-the-virtual-memory-address-spaces.patch
------------------------------------------------------
From: SeongJae Park <sjpark@xxxxxxxxx>
Subject: mm/damon/vaddr: safely walk page table
Commit d7f647622761 ("mm/damon: implement primitives for the virtual
memory address spaces") of linux-mm[1] tries to find PTE or PMD for
arbitrary virtual address using 'follow_invalidate_pte()' without proper
locking[2]. This commit fixes the issue by using another page table walk
function for more general use case ('walk_page_range()') under proper
locking (holding mmap read lock).
[1] https://github.com/hnaz/linux-mm/commit/d7f647622761
[2] https://lore.kernel.org/linux-mm/3b094493-9c1e-6024-bfd5-7eca66399b7e@xxxxxxxxxx
Link: https://lkml.kernel.org/r/20210831161800.29419-1-sj38.park@xxxxxxxxx
Fixes: d7f647622761 ("mm/damon: implement primitives for the virtual memory address spaces")
Signed-off-by: SeongJae Park <sjpark@xxxxxxxxx>
Reported-by: David Hildenbrand <david@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/damon/vaddr.c | 136 ++++++++++++++++++++++++++++++++-------------
1 file changed, 97 insertions(+), 39 deletions(-)
--- a/mm/damon/vaddr.c~mm-damon-implement-primitives-for-the-virtual-memory-address-spaces-fix-3
+++ a/mm/damon/vaddr.c
@@ -8,10 +8,12 @@
#define pr_fmt(fmt) "damon-va: " fmt
#include <linux/damon.h>
+#include <linux/hugetlb.h>
#include <linux/mm.h>
#include <linux/mmu_notifier.h>
#include <linux/highmem.h>
#include <linux/page_idle.h>
+#include <linux/pagewalk.h>
#include <linux/random.h>
#include <linux/sched/mm.h>
#include <linux/slab.h>
@@ -441,22 +443,42 @@ static void damon_pmdp_mkold(pmd_t *pmd,
#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
}
-static void damon_va_mkold(struct mm_struct *mm, unsigned long addr)
+static int damon_mkold_pmd_entry(pmd_t *pmd, unsigned long addr,
+ unsigned long next, struct mm_walk *walk)
{
- pte_t *pte = NULL;
- pmd_t *pmd = NULL;
+ pte_t *pte;
spinlock_t *ptl;
- if (follow_invalidate_pte(mm, addr, NULL, &pte, &pmd, &ptl))
- return;
-
- if (pte) {
- damon_ptep_mkold(pte, mm, addr);
- pte_unmap_unlock(pte, ptl);
- } else {
- damon_pmdp_mkold(pmd, mm, addr);
+ if (pmd_huge(*pmd)) {
+ ptl = pmd_lock(walk->mm, pmd);
+ if (pmd_huge(*pmd)) {
+ damon_pmdp_mkold(pmd, walk->mm, addr);
+ spin_unlock(ptl);
+ return 0;
+ }
spin_unlock(ptl);
}
+
+ if (pmd_none(*pmd) || unlikely(pmd_bad(*pmd)))
+ return 0;
+ pte = pte_offset_map_lock(walk->mm, pmd, addr, &ptl);
+ if (!pte_present(*pte))
+ goto out;
+ damon_ptep_mkold(pte, walk->mm, addr);
+out:
+ pte_unmap_unlock(pte, ptl);
+ return 0;
+}
+
+static struct mm_walk_ops damon_mkold_ops = {
+ .pmd_entry = damon_mkold_pmd_entry,
+};
+
+static void damon_va_mkold(struct mm_struct *mm, unsigned long addr)
+{
+ mmap_read_lock(mm);
+ walk_page_range(mm, addr, addr + 1, &damon_mkold_ops, NULL);
+ mmap_read_unlock(mm);
}
/*
@@ -487,43 +509,79 @@ void damon_va_prepare_access_checks(stru
}
}
-static bool damon_va_young(struct mm_struct *mm, unsigned long addr,
- unsigned long *page_sz)
+struct damon_young_walk_private {
+ unsigned long *page_sz;
+ bool young;
+};
+
+static int damon_young_pmd_entry(pmd_t *pmd, unsigned long addr,
+ unsigned long next, struct mm_walk *walk)
{
- pte_t *pte = NULL;
- pmd_t *pmd = NULL;
+ pte_t *pte;
spinlock_t *ptl;
struct page *page;
- bool young = false;
-
- if (follow_invalidate_pte(mm, addr, NULL, &pte, &pmd, &ptl))
- return false;
-
- *page_sz = PAGE_SIZE;
- if (pte) {
- page = damon_get_page(pte_pfn(*pte));
- if (page && (pte_young(*pte) || !page_is_idle(page) ||
- mmu_notifier_test_young(mm, addr)))
- young = true;
- if (page)
- put_page(page);
- pte_unmap_unlock(pte, ptl);
- return young;
- }
+ struct damon_young_walk_private *priv = walk->private;
#ifdef CONFIG_TRANSPARENT_HUGEPAGE
- page = damon_get_page(pmd_pfn(*pmd));
- if (page && (pmd_young(*pmd) || !page_is_idle(page) ||
- mmu_notifier_test_young(mm, addr)))
- young = true;
- if (page)
+ if (pmd_huge(*pmd)) {
+ ptl = pmd_lock(walk->mm, pmd);
+ if (!pmd_huge(*pmd)) {
+ spin_unlock(ptl);
+ goto regular_page;
+ }
+ page = damon_get_page(pmd_pfn(*pmd));
+ if (!page)
+ goto huge_out;
+ if (pmd_young(*pmd) || !page_is_idle(page) ||
+ mmu_notifier_test_young(walk->mm,
+ addr)) {
+ *priv->page_sz = ((1UL) << HPAGE_PMD_SHIFT);
+ priv->young = true;
+ }
put_page(page);
+huge_out:
+ spin_unlock(ptl);
+ return 0;
+ }
- spin_unlock(ptl);
- *page_sz = ((1UL) << HPAGE_PMD_SHIFT);
+regular_page:
#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
- return young;
+ if (pmd_none(*pmd) || unlikely(pmd_bad(*pmd)))
+ return -EINVAL;
+ pte = pte_offset_map_lock(walk->mm, pmd, addr, &ptl);
+ if (!pte_present(*pte))
+ goto out;
+ page = damon_get_page(pte_pfn(*pte));
+ if (!page)
+ goto out;
+ if (pte_young(*pte) || !page_is_idle(page) ||
+ mmu_notifier_test_young(walk->mm, addr)) {
+ *priv->page_sz = PAGE_SIZE;
+ priv->young = true;
+ }
+ put_page(page);
+out:
+ pte_unmap_unlock(pte, ptl);
+ return 0;
+}
+
+static struct mm_walk_ops damon_young_ops = {
+ .pmd_entry = damon_young_pmd_entry,
+};
+
+static bool damon_va_young(struct mm_struct *mm, unsigned long addr,
+ unsigned long *page_sz)
+{
+ struct damon_young_walk_private arg = {
+ .page_sz = page_sz,
+ .young = false,
+ };
+
+ mmap_read_lock(mm);
+ walk_page_range(mm, addr, addr + 1, &damon_young_ops, &arg);
+ mmap_read_unlock(mm);
+ return arg.young;
}
/*
_
Patches currently in -mm which might be from sjpark@xxxxxxxxx are
mm-introduce-data-access-monitor-damon.patch
mm-damon-core-implement-region-based-sampling.patch
mm-damon-adaptively-adjust-regions.patch
mm-idle_page_tracking-make-pg_idle-reusable.patch
mm-damon-implement-primitives-for-the-virtual-memory-address-spaces.patch
mm-damon-add-a-tracepoint.patch
mm-damon-implement-a-debugfs-based-user-space-interface.patch
mm-damon-dbgfs-export-kdamond-pid-to-the-user-space.patch
mm-damon-dbgfs-support-multiple-contexts.patch
documentation-add-documents-for-damon.patch
mm-damon-add-kunit-tests.patch
mm-damon-add-user-space-selftests.patch
maintainers-update-for-damon.patch
