From: Cyrill Gorcunov <gorcunov@xxxxxxxxx>
Subject: mm: migration: do not lose soft dirty bit if page is in migration state
If page migration is turned on in config and the page is migrating, we may
lose the soft dirty bit. If fork and mprotect are called on migrating
pages (once migration is complete) pages do not obtain the soft dirty bit
in the correspond pte entries. Fix it adding an appropriate test on swap
entries.
Signed-off-by: Cyrill Gorcunov <gorcunov@xxxxxxxxxx>
Cc: Pavel Emelyanov <xemul@xxxxxxxxxxxxx>
Cc: Andy Lutomirski <luto@xxxxxxxxxxxxxx>
Cc: Matt Mackall <mpm@xxxxxxxxxxx>
Cc: Xiao Guangrong <xiaoguangrong@xxxxxxxxxxxxxxxxxx>
Cc: Marcelo Tosatti <mtosatti@xxxxxxxxxx>
Cc: KOSAKI Motohiro <kosaki.motohiro@xxxxxxxxx>
Cc: Stephen Rothwell <sfr@xxxxxxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: "Aneesh Kumar K.V" <aneesh.kumar@xxxxxxxxxxxxxxxxxx>
Cc: Naoya Horiguchi <n-horiguchi@xxxxxxxxxxxxx>
Cc: Mel Gorman <mel@xxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/memory.c | 2 ++
mm/migrate.c | 2 ++
mm/mprotect.c | 7 +++++--
3 files changed, 9 insertions(+), 2 deletions(-)
diff -puN mm/memory.c~mm-migration-do-not-lose-soft-dirty-bit-if-page-is-in-migration-state mm/memory.c
--- a/mm/memory.c~mm-migration-do-not-lose-soft-dirty-bit-if-page-is-in-migration-state
+++ a/mm/memory.c
@@ -837,6 +837,8 @@ copy_one_pte(struct mm_struct *dst_mm, s
*/
make_migration_entry_read(&entry);
pte = swp_entry_to_pte(entry);
+ if (pte_swp_soft_dirty(*src_pte))
+ pte = pte_swp_mksoft_dirty(pte);
set_pte_at(src_mm, addr, src_pte, pte);
}
}
diff -puN mm/migrate.c~mm-migration-do-not-lose-soft-dirty-bit-if-page-is-in-migration-state mm/migrate.c
--- a/mm/migrate.c~mm-migration-do-not-lose-soft-dirty-bit-if-page-is-in-migration-state
+++ a/mm/migrate.c
@@ -161,6 +161,8 @@ static int remove_migration_pte(struct p
get_page(new);
pte = pte_mkold(mk_pte(new, vma->vm_page_prot));
+ if (pte_swp_soft_dirty(*ptep))
+ pte = pte_mksoft_dirty(pte);
if (is_write_migration_entry(entry))
pte = pte_mkwrite(pte);
#ifdef CONFIG_HUGETLB_PAGE
diff -puN mm/mprotect.c~mm-migration-do-not-lose-soft-dirty-bit-if-page-is-in-migration-state mm/mprotect.c
--- a/mm/mprotect.c~mm-migration-do-not-lose-soft-dirty-bit-if-page-is-in-migration-state
+++ a/mm/mprotect.c
@@ -94,13 +94,16 @@ static unsigned long change_pte_range(st
swp_entry_t entry = pte_to_swp_entry(oldpte);
if (is_write_migration_entry(entry)) {
+ pte_t newpte;
/*
* A protection check is difficult so
* just be safe and disable write
*/
make_migration_entry_read(&entry);
- set_pte_at(mm, addr, pte,
- swp_entry_to_pte(entry));
+ newpte = swp_entry_to_pte(entry);
+ if (pte_swp_soft_dirty(oldpte))
+ newpte = pte_swp_mksoft_dirty(newpte);
+ set_pte_at(mm, addr, pte, newpte);
}
pages++;
}
_
--
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