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-rw-r--r--mm/huge_memory.c9
-rw-r--r--mm/memory.c8
-rw-r--r--mm/mprotect.c3
3 files changed, 14 insertions, 6 deletions
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 2f12e9fcf1a2..0a42d1521aa4 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -1260,6 +1260,7 @@ int do_huge_pmd_numa_page(struct mm_struct *mm, struct vm_area_struct *vma,
int target_nid, last_cpupid = -1;
bool page_locked;
bool migrated = false;
+ bool was_writable;
int flags = 0;
/* A PROT_NONE fault should not end up here */
@@ -1354,7 +1355,10 @@ int do_huge_pmd_numa_page(struct mm_struct *mm, struct vm_area_struct *vma,
goto out;
clear_pmdnuma:
BUG_ON(!PageLocked(page));
+ was_writable = pmd_write(pmd);
pmd = pmd_modify(pmd, vma->vm_page_prot);
+ if (was_writable)
+ pmd = pmd_mkwrite(pmd);
set_pmd_at(mm, haddr, pmdp, pmd);
update_mmu_cache_pmd(vma, addr, pmdp);
unlock_page(page);
@@ -1478,6 +1482,7 @@ int change_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,
if (__pmd_trans_huge_lock(pmd, vma, &ptl) == 1) {
pmd_t entry;
+ bool preserve_write = prot_numa && pmd_write(*pmd);
ret = 1;
/*
@@ -1493,9 +1498,11 @@ int change_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,
if (!prot_numa || !pmd_protnone(*pmd)) {
entry = pmdp_get_and_clear_notify(mm, addr, pmd);
entry = pmd_modify(entry, newprot);
+ if (preserve_write)
+ entry = pmd_mkwrite(entry);
ret = HPAGE_PMD_NR;
set_pmd_at(mm, addr, pmd, entry);
- BUG_ON(pmd_write(entry));
+ BUG_ON(!preserve_write && pmd_write(entry));
}
spin_unlock(ptl);
}
diff --git a/mm/memory.c b/mm/memory.c
index 20beb6647dba..d20e12da3a3c 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -3035,6 +3035,7 @@ static int do_numa_page(struct mm_struct *mm, struct vm_area_struct *vma,
int last_cpupid;
int target_nid;
bool migrated = false;
+ bool was_writable = pte_write(pte);
int flags = 0;
/* A PROT_NONE fault should not end up here */
@@ -3059,6 +3060,8 @@ static int do_numa_page(struct mm_struct *mm, struct vm_area_struct *vma,
/* Make it present again */
pte = pte_modify(pte, vma->vm_page_prot);
pte = pte_mkyoung(pte);
+ if (was_writable)
+ pte = pte_mkwrite(pte);
set_pte_at(mm, addr, ptep, pte);
update_mmu_cache(vma, addr, ptep);
@@ -3075,11 +3078,6 @@ static int do_numa_page(struct mm_struct *mm, struct vm_area_struct *vma,
* to it but pte_write gets cleared during protection updates and
* pte_dirty has unpredictable behaviour between PTE scan updates,
* background writeback, dirty balancing and application behaviour.
- *
- * TODO: Note that the ideal here would be to avoid a situation where a
- * NUMA fault is taken immediately followed by a write fault in
- * some cases which would have lower overhead overall but would be
- * invasive as the fault paths would need to be unified.
*/
if (!(vma->vm_flags & VM_WRITE))
flags |= TNF_NO_GROUP;
diff --git a/mm/mprotect.c b/mm/mprotect.c
index 44727811bf4c..88584838e704 100644
--- a/mm/mprotect.c
+++ b/mm/mprotect.c
@@ -75,6 +75,7 @@ static unsigned long change_pte_range(struct vm_area_struct *vma, pmd_t *pmd,
oldpte = *pte;
if (pte_present(oldpte)) {
pte_t ptent;
+ bool preserve_write = prot_numa && pte_write(oldpte);
/*
* Avoid trapping faults against the zero or KSM
@@ -94,6 +95,8 @@ static unsigned long change_pte_range(struct vm_area_struct *vma, pmd_t *pmd,
ptent = ptep_modify_prot_start(mm, addr, pte);
ptent = pte_modify(ptent, newprot);
+ if (preserve_write)
+ ptent = pte_mkwrite(ptent);
/* Avoid taking write faults for known dirty pages */
if (dirty_accountable && pte_dirty(ptent) &&