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authorJuergen Gross <jgross@suse.com>2022-11-23 09:45:10 +0300
committerAndrew Morton <akpm@linux-foundation.org>2022-12-01 01:49:41 +0300
commit4aaf269c768dbacd6268af73fda2ffccaa3f1d88 (patch)
tree33b5f4fb5b5fc66701c0e74fc738d6f556cb2c9a /mm
parent6617da8fb565445e0be4a4885443006374943d09 (diff)
downloadlinux-4aaf269c768dbacd6268af73fda2ffccaa3f1d88.tar.xz
mm: introduce arch_has_hw_nonleaf_pmd_young()
When running as a Xen PV guests commit eed9a328aa1a ("mm: x86: add CONFIG_ARCH_HAS_NONLEAF_PMD_YOUNG") can cause a protection violation in pmdp_test_and_clear_young(): BUG: unable to handle page fault for address: ffff8880083374d0 #PF: supervisor write access in kernel mode #PF: error_code(0x0003) - permissions violation PGD 3026067 P4D 3026067 PUD 3027067 PMD 7fee5067 PTE 8010000008337065 Oops: 0003 [#1] PREEMPT SMP NOPTI CPU: 7 PID: 158 Comm: kswapd0 Not tainted 6.1.0-rc5-20221118-doflr+ #1 RIP: e030:pmdp_test_and_clear_young+0x25/0x40 This happens because the Xen hypervisor can't emulate direct writes to page table entries other than PTEs. This can easily be fixed by introducing arch_has_hw_nonleaf_pmd_young() similar to arch_has_hw_pte_young() and test that instead of CONFIG_ARCH_HAS_NONLEAF_PMD_YOUNG. Link: https://lkml.kernel.org/r/20221123064510.16225-1-jgross@suse.com Fixes: eed9a328aa1a ("mm: x86: add CONFIG_ARCH_HAS_NONLEAF_PMD_YOUNG") Signed-off-by: Juergen Gross <jgross@suse.com> Reported-by: Sander Eikelenboom <linux@eikelenboom.it> Acked-by: Yu Zhao <yuzhao@google.com> Tested-by: Sander Eikelenboom <linux@eikelenboom.it> Acked-by: David Hildenbrand <david@redhat.com> [core changes] Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'mm')
-rw-r--r--mm/vmscan.c10
1 files changed, 5 insertions, 5 deletions
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 026199c047e0..8fcc5fa768c0 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -3987,7 +3987,7 @@ static void walk_pmd_range_locked(pud_t *pud, unsigned long next, struct vm_area
goto next;
if (!pmd_trans_huge(pmd[i])) {
- if (IS_ENABLED(CONFIG_ARCH_HAS_NONLEAF_PMD_YOUNG) &&
+ if (arch_has_hw_nonleaf_pmd_young() &&
get_cap(LRU_GEN_NONLEAF_YOUNG))
pmdp_test_and_clear_young(vma, addr, pmd + i);
goto next;
@@ -4085,14 +4085,14 @@ restart:
#endif
walk->mm_stats[MM_NONLEAF_TOTAL]++;
-#ifdef CONFIG_ARCH_HAS_NONLEAF_PMD_YOUNG
- if (get_cap(LRU_GEN_NONLEAF_YOUNG)) {
+ if (arch_has_hw_nonleaf_pmd_young() &&
+ get_cap(LRU_GEN_NONLEAF_YOUNG)) {
if (!pmd_young(val))
continue;
walk_pmd_range_locked(pud, addr, vma, args, bitmap, &pos);
}
-#endif
+
if (!walk->force_scan && !test_bloom_filter(walk->lruvec, walk->max_seq, pmd + i))
continue;
@@ -5392,7 +5392,7 @@ static ssize_t show_enabled(struct kobject *kobj, struct kobj_attribute *attr, c
if (arch_has_hw_pte_young() && get_cap(LRU_GEN_MM_WALK))
caps |= BIT(LRU_GEN_MM_WALK);
- if (IS_ENABLED(CONFIG_ARCH_HAS_NONLEAF_PMD_YOUNG) && get_cap(LRU_GEN_NONLEAF_YOUNG))
+ if (arch_has_hw_nonleaf_pmd_young() && get_cap(LRU_GEN_NONLEAF_YOUNG))
caps |= BIT(LRU_GEN_NONLEAF_YOUNG);
return snprintf(buf, PAGE_SIZE, "0x%04x\n", caps);