The patch titled
Subject: fix mremap bug of failing to split thp
has been added to the -mm tree. Its filename is
thp-optimize-away-unnecessary-page-table-locking-fix.patch
Before you just go and hit "reply", please:
a) Consider who else should be cc'ed
b) Prefer to cc a suitable mailing list as well
c) Ideally: find the original patch on the mailing list and do a
reply-to-all to that, adding suitable additional cc's
*** Remember to use Documentation/SubmitChecklist when testing your code ***
The -mm tree is included into linux-next and is updated
there every 3-4 working days
------------------------------------------------------
From: Naoya Horiguchi <n-horiguchi@xxxxxxxxxxxxx>
Subject: fix mremap bug of failing to split thp
The patch "thp: optimize away unnecessary page table locking" introduced a
bug to move_page_tables(), where we fail to split thp when move_huge_pmd()
is not called. To fix it, this patch reverts the return value changes and
readd if (!err) block.
Signed-off-by: Naoya Horiguchi <n-horiguchi@xxxxxxxxxxxxx>
Cc: David Rientjes <rientjes@xxxxxxxxxx>
Cc: Andi Kleen <andi@xxxxxxxxxxxxxx>
Cc: Wu Fengguang <fengguang.wu@xxxxxxxxx>
Cc: Andrea Arcangeli <aarcange@xxxxxxxxxx>
Cc: KOSAKI Motohiro <kosaki.motohiro@xxxxxxxxxxxxxx>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>
Cc: Jiri Slaby <jslaby@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
fs/proc/task_mmu.c | 6 +++---
mm/huge_memory.c | 13 ++++++-------
mm/mremap.c | 2 ++
3 files changed, 11 insertions(+), 10 deletions(-)
diff -puN fs/proc/task_mmu.c~thp-optimize-away-unnecessary-page-table-locking-fix fs/proc/task_mmu.c
--- a/fs/proc/task_mmu.c~thp-optimize-away-unnecessary-page-table-locking-fix
+++ a/fs/proc/task_mmu.c
@@ -394,7 +394,7 @@ static int smaps_pte_range(pmd_t *pmd, u
pte_t *pte;
spinlock_t *ptl;
- if (pmd_trans_huge_lock(pmd, vma)) {
+ if (pmd_trans_huge_lock(pmd, vma) == 1) {
smaps_pte_entry(*(pte_t *)pmd, addr, HPAGE_PMD_SIZE, walk);
spin_unlock(&walk->mm->page_table_lock);
mss->anonymous_thp += HPAGE_PMD_SIZE;
@@ -688,7 +688,7 @@ static int pagemap_pte_range(pmd_t *pmd,
/* find the first VMA at or above 'addr' */
vma = find_vma(walk->mm, addr);
- if (pmd_trans_huge_lock(pmd, vma)) {
+ if (pmd_trans_huge_lock(pmd, vma) == 1) {
for (; addr != end; addr += PAGE_SIZE) {
unsigned long offset = (addr & ~PAGEMAP_WALK_MASK)
>> PAGE_SHIFT;
@@ -966,7 +966,7 @@ static int gather_pte_stats(pmd_t *pmd,
md = walk->private;
- if (pmd_trans_huge_lock(pmd, md->vma)) {
+ if (pmd_trans_huge_lock(pmd, md->vma) == 1) {
pte_t huge_pte = *(pte_t *)pmd;
struct page *page;
diff -puN mm/huge_memory.c~thp-optimize-away-unnecessary-page-table-locking-fix mm/huge_memory.c
--- a/mm/huge_memory.c~thp-optimize-away-unnecessary-page-table-locking-fix
+++ a/mm/huge_memory.c
@@ -1030,7 +1030,7 @@ int zap_huge_pmd(struct mmu_gather *tlb,
{
int ret = 0;
- if (__pmd_trans_huge_lock(pmd, vma)) {
+ if (__pmd_trans_huge_lock(pmd, vma) == 1) {
struct page *page;
pgtable_t pgtable;
pgtable = get_pmd_huge_pte(tlb->mm);
@@ -1056,7 +1056,7 @@ int mincore_huge_pmd(struct vm_area_stru
{
int ret = 0;
- if (__pmd_trans_huge_lock(pmd, vma)) {
+ if (__pmd_trans_huge_lock(pmd, vma) == 1) {
/*
* All logical pages in the range are present
* if backed by a huge page.
@@ -1094,12 +1094,11 @@ int move_huge_pmd(struct vm_area_struct
goto out;
}
- if (__pmd_trans_huge_lock(old_pmd, vma)) {
+ if ((ret = __pmd_trans_huge_lock(old_pmd, vma)) == 1) {
pmd = pmdp_get_and_clear(mm, old_addr, old_pmd);
VM_BUG_ON(!pmd_none(*new_pmd));
set_pmd_at(mm, new_addr, new_pmd, pmd);
spin_unlock(&mm->page_table_lock);
- ret = 1;
}
out:
return ret;
@@ -1111,7 +1110,7 @@ int change_huge_pmd(struct vm_area_struc
struct mm_struct *mm = vma->vm_mm;
int ret = 0;
- if (__pmd_trans_huge_lock(pmd, vma)) {
+ if (__pmd_trans_huge_lock(pmd, vma) == 1) {
pmd_t entry;
entry = pmdp_get_and_clear(mm, addr, pmd);
entry = pmd_modify(entry, newprot);
@@ -1125,7 +1124,7 @@ int change_huge_pmd(struct vm_area_struc
/*
* Returns 1 if a given pmd maps a stable (not under splitting) thp.
- * Returns 0 otherwise.
+ * Returns -1 if it maps a thp under splitting. Returns 0 otherwise.
*
* Note that if it returns 1, this routine returns without unlocking page
* table locks. So callers must unlock them.
@@ -1137,7 +1136,7 @@ int __pmd_trans_huge_lock(pmd_t *pmd, st
if (unlikely(pmd_trans_splitting(*pmd))) {
spin_unlock(&vma->vm_mm->page_table_lock);
wait_split_huge_page(vma->anon_vma, pmd);
- return 0;
+ return -1;
} else {
/* Thp mapped by 'pmd' is stable, so we can
* handle it as it is. */
diff -puN mm/mremap.c~thp-optimize-away-unnecessary-page-table-locking-fix mm/mremap.c
--- a/mm/mremap.c~thp-optimize-away-unnecessary-page-table-locking-fix
+++ a/mm/mremap.c
@@ -155,6 +155,8 @@ unsigned long move_page_tables(struct vm
if (err > 0) {
need_flush = true;
continue;
+ } else if (!err) {
+ split_huge_page_pmd(vma->vm_mm, old_pmd);
}
VM_BUG_ON(pmd_trans_huge(*old_pmd));
}
_
Subject: Subject: fix mremap bug of failing to split thp
Patches currently in -mm which might be from n-horiguchi@xxxxxxxxxxxxx are
pagemap-avoid-splitting-thp-when-reading-proc-pid-pagemap.patch
thp-optimize-away-unnecessary-page-table-locking.patch
thp-optimize-away-unnecessary-page-table-locking-fix.patch
thp-optimize-away-unnecessary-page-table-locking-fix-checkpatch-fixes.patch
pagemap-export-kpf_thp.patch
pagemap-document-kpf_thp-and-make-page-types-aware-of-it.patch
pagemap-introduce-data-structure-for-pagemap-entry.patch
--
To unsubscribe from this list: send the line "unsubscribe mm-commits" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
