Re: [PATCH v18 25/32] mm/mlock: remove lru_lock on TestClearPageMlocked in munlock_vma_page
在 2020/9/22 下午2:13, Hugh Dickins 写道: > On Mon, 24 Aug 2020, Alex Shi wrote: > >> In the func munlock_vma_page, the page must be PageLocked as well as >> pages in split_huge_page series funcs. Thus the PageLocked is enough >> to serialize both funcs. >> >> So we could relief the TestClearPageMlocked/hpage_nr_pages which are not >> necessary under lru lock. >> >> As to another munlock func __munlock_pagevec, which no PageLocked >> protection and should remain lru protecting. >> >> Signed-off-by: Alex Shi > I made some comments on the mlock+munlock situation last week: > I won't review this 24/32 and 25/32 now, but will take a look > at your github tree tomorrow instead. Perhaps I'll find you have > already done the fixes, perhaps I'll find you have merged these back > into earlier patches. And I won't be reviewing beyond this point: > this is enough for now, I think. > Yes, these 2 patches was fixed as your suggested on https://github.com/alexshi/linux.git lruv19.5 83f8582dcd5a mm/mlock: remove lru_lock on TestClearPageMlocked 20836d10f0ed mm/mlock: remove __munlock_isolate_lru_page Thanks! Alex
Re: [PATCH v18 25/32] mm/mlock: remove lru_lock on TestClearPageMlocked in munlock_vma_page
On Mon, 24 Aug 2020, Alex Shi wrote:
> In the func munlock_vma_page, the page must be PageLocked as well as
> pages in split_huge_page series funcs. Thus the PageLocked is enough
> to serialize both funcs.
>
> So we could relief the TestClearPageMlocked/hpage_nr_pages which are not
> necessary under lru lock.
>
> As to another munlock func __munlock_pagevec, which no PageLocked
> protection and should remain lru protecting.
>
> Signed-off-by: Alex Shi
I made some comments on the mlock+munlock situation last week:
I won't review this 24/32 and 25/32 now, but will take a look
at your github tree tomorrow instead. Perhaps I'll find you have
already done the fixes, perhaps I'll find you have merged these back
into earlier patches. And I won't be reviewing beyond this point:
this is enough for now, I think.
Hugh
> Cc: Kirill A. Shutemov
> Cc: Vlastimil Babka
> Cc: Andrew Morton
> Cc: linux...@kvack.org
> Cc: linux-kernel@vger.kernel.org
> ---
> mm/mlock.c | 41 +++--
> 1 file changed, 15 insertions(+), 26 deletions(-)
>
> diff --git a/mm/mlock.c b/mm/mlock.c
> index 0448409184e3..46a05e6ec5ba 100644
> --- a/mm/mlock.c
> +++ b/mm/mlock.c
> @@ -69,9 +69,9 @@ void clear_page_mlock(struct page *page)
>*
>* See __pagevec_lru_add_fn for more explanation.
>*/
> - if (!isolate_lru_page(page)) {
> + if (!isolate_lru_page(page))
> putback_lru_page(page);
> - } else {
> + else {
> /*
>* We lost the race. the page already moved to evictable list.
>*/
> @@ -178,7 +178,6 @@ static void __munlock_isolation_failed(struct page *page)
> unsigned int munlock_vma_page(struct page *page)
> {
> int nr_pages;
> - struct lruvec *lruvec;
>
> /* For try_to_munlock() and to serialize with page migration */
> BUG_ON(!PageLocked(page));
> @@ -186,37 +185,22 @@ unsigned int munlock_vma_page(struct page *page)
> VM_BUG_ON_PAGE(PageTail(page), page);
>
> /*
> - * Serialize split tail pages in __split_huge_page_tail() which
> - * might otherwise copy PageMlocked to part of the tail pages before
> - * we clear it in the head page. It also stabilizes thp_nr_pages().
> - * TestClearPageLRU can't be used here to block page isolation, since
> - * out of lock clear_page_mlock may interfer PageLRU/PageMlocked
> - * sequence, same as __pagevec_lru_add_fn, and lead the page place to
> - * wrong lru list here. So relay on PageLocked to stop lruvec change
> - * in mem_cgroup_move_account().
> + * Serialize split tail pages in __split_huge_page_tail() by
> + * lock_page(); Do TestClearPageMlocked/PageLRU sequence like
> + * clear_page_mlock().
>*/
> - lruvec = lock_page_lruvec_irq(page);
> -
> - if (!TestClearPageMlocked(page)) {
> + if (!TestClearPageMlocked(page))
> /* Potentially, PTE-mapped THP: do not skip the rest PTEs */
> - nr_pages = 1;
> - goto unlock_out;
> - }
> + return 0;
>
> nr_pages = thp_nr_pages(page);
> __mod_zone_page_state(page_zone(page), NR_MLOCK, -nr_pages);
>
> - if (__munlock_isolate_lru_page(page, lruvec, true)) {
> - unlock_page_lruvec_irq(lruvec);
> + if (!isolate_lru_page(page))
> __munlock_isolated_page(page);
> - goto out;
> - }
> - __munlock_isolation_failed(page);
> -
> -unlock_out:
> - unlock_page_lruvec_irq(lruvec);
> + else
> + __munlock_isolation_failed(page);
>
> -out:
> return nr_pages - 1;
> }
>
> @@ -305,6 +289,11 @@ static void __munlock_pagevec(struct pagevec *pvec,
> struct zone *zone)
>
> /* block memcg change in mem_cgroup_move_account */
> lock_page_memcg(page);
> + /*
> + * Serialize split tail pages in __split_huge_page_tail() which
> + * might otherwise copy PageMlocked to part of the tail pages
> + * before we clear it in the head page.
> + */
> lruvec = relock_page_lruvec_irq(page, lruvec);
> if (TestClearPageMlocked(page)) {
> /*
> --
> 1.8.3.1
>
>
Re: [PATCH v18 25/32] mm/mlock: remove lru_lock on TestClearPageMlocked in munlock_vma_page
LKP reported a preemptiable issue on this patch. update and refresh
the commit log.
>From f18e8c87a045bbb8040006b6816ded1f55fa6f9c Mon Sep 17 00:00:00 2001
From: Alex Shi
Date: Sat, 25 Jul 2020 22:31:03 +0800
Subject: [PATCH] mm/mlock: remove lru_lock on TestClearPageMlocked in
munlock_vma_page
In the func munlock_vma_page, comments mentained lru_lock needed for
serialization with split_huge_pages. But the page must be PageLocked
as well as pages in split_huge_page series funcs. Thus the PageLocked
is enough to serialize both funcs.
So we could relief the TestClearPageMlocked/hpage_nr_pages which are not
necessary under lru lock.
As to another munlock func __munlock_pagevec, which no PageLocked
protection and should remain lru protecting.
LKP found a preempt issue on __mod_zone_page_state which need change
to mod_zone_page_state. Thanks!
Reported-by: kernel test robot
Signed-off-by: Alex Shi
Cc: Kirill A. Shutemov
Cc: Vlastimil Babka
Cc: Andrew Morton
Cc: linux...@kvack.org
Cc: linux-kernel@vger.kernel.org
---
mm/mlock.c | 43 ---
1 file changed, 16 insertions(+), 27 deletions(-)
diff --git a/mm/mlock.c b/mm/mlock.c
index 0448409184e3..cd88b93b0f0d 100644
--- a/mm/mlock.c
+++ b/mm/mlock.c
@@ -69,9 +69,9 @@ void clear_page_mlock(struct page *page)
*
* See __pagevec_lru_add_fn for more explanation.
*/
- if (!isolate_lru_page(page)) {
+ if (!isolate_lru_page(page))
putback_lru_page(page);
- } else {
+ else {
/*
* We lost the race. the page already moved to evictable list.
*/
@@ -178,7 +178,6 @@ static void __munlock_isolation_failed(struct page *page)
unsigned int munlock_vma_page(struct page *page)
{
int nr_pages;
- struct lruvec *lruvec;
/* For try_to_munlock() and to serialize with page migration */
BUG_ON(!PageLocked(page));
@@ -186,37 +185,22 @@ unsigned int munlock_vma_page(struct page *page)
VM_BUG_ON_PAGE(PageTail(page), page);
/*
-* Serialize split tail pages in __split_huge_page_tail() which
-* might otherwise copy PageMlocked to part of the tail pages before
-* we clear it in the head page. It also stabilizes thp_nr_pages().
-* TestClearPageLRU can't be used here to block page isolation, since
-* out of lock clear_page_mlock may interfer PageLRU/PageMlocked
-* sequence, same as __pagevec_lru_add_fn, and lead the page place to
-* wrong lru list here. So relay on PageLocked to stop lruvec change
-* in mem_cgroup_move_account().
+* Serialize split tail pages in __split_huge_page_tail() by
+* lock_page(); Do TestClearPageMlocked/PageLRU sequence like
+* clear_page_mlock().
*/
- lruvec = lock_page_lruvec_irq(page);
-
- if (!TestClearPageMlocked(page)) {
+ if (!TestClearPageMlocked(page))
/* Potentially, PTE-mapped THP: do not skip the rest PTEs */
- nr_pages = 1;
- goto unlock_out;
- }
+ return 0;
nr_pages = thp_nr_pages(page);
- __mod_zone_page_state(page_zone(page), NR_MLOCK, -nr_pages);
+ mod_zone_page_state(page_zone(page), NR_MLOCK, -nr_pages);
- if (__munlock_isolate_lru_page(page, lruvec, true)) {
- unlock_page_lruvec_irq(lruvec);
+ if (!isolate_lru_page(page))
__munlock_isolated_page(page);
- goto out;
- }
- __munlock_isolation_failed(page);
-
-unlock_out:
- unlock_page_lruvec_irq(lruvec);
+ else
+ __munlock_isolation_failed(page);
-out:
return nr_pages - 1;
}
@@ -305,6 +289,11 @@ static void __munlock_pagevec(struct pagevec *pvec, struct
zone *zone)
/* block memcg change in mem_cgroup_move_account */
lock_page_memcg(page);
+ /*
+* Serialize split tail pages in __split_huge_page_tail() which
+* might otherwise copy PageMlocked to part of the tail pages
+* before we clear it in the head page.
+*/
lruvec = relock_page_lruvec_irq(page, lruvec);
if (TestClearPageMlocked(page)) {
/*
--
2.17.1
[PATCH v18 25/32] mm/mlock: remove lru_lock on TestClearPageMlocked in munlock_vma_page
In the func munlock_vma_page, the page must be PageLocked as well as
pages in split_huge_page series funcs. Thus the PageLocked is enough
to serialize both funcs.
So we could relief the TestClearPageMlocked/hpage_nr_pages which are not
necessary under lru lock.
As to another munlock func __munlock_pagevec, which no PageLocked
protection and should remain lru protecting.
Signed-off-by: Alex Shi
Cc: Kirill A. Shutemov
Cc: Vlastimil Babka
Cc: Andrew Morton
Cc: linux...@kvack.org
Cc: linux-kernel@vger.kernel.org
---
mm/mlock.c | 41 +++--
1 file changed, 15 insertions(+), 26 deletions(-)
diff --git a/mm/mlock.c b/mm/mlock.c
index 0448409184e3..46a05e6ec5ba 100644
--- a/mm/mlock.c
+++ b/mm/mlock.c
@@ -69,9 +69,9 @@ void clear_page_mlock(struct page *page)
*
* See __pagevec_lru_add_fn for more explanation.
*/
- if (!isolate_lru_page(page)) {
+ if (!isolate_lru_page(page))
putback_lru_page(page);
- } else {
+ else {
/*
* We lost the race. the page already moved to evictable list.
*/
@@ -178,7 +178,6 @@ static void __munlock_isolation_failed(struct page *page)
unsigned int munlock_vma_page(struct page *page)
{
int nr_pages;
- struct lruvec *lruvec;
/* For try_to_munlock() and to serialize with page migration */
BUG_ON(!PageLocked(page));
@@ -186,37 +185,22 @@ unsigned int munlock_vma_page(struct page *page)
VM_BUG_ON_PAGE(PageTail(page), page);
/*
-* Serialize split tail pages in __split_huge_page_tail() which
-* might otherwise copy PageMlocked to part of the tail pages before
-* we clear it in the head page. It also stabilizes thp_nr_pages().
-* TestClearPageLRU can't be used here to block page isolation, since
-* out of lock clear_page_mlock may interfer PageLRU/PageMlocked
-* sequence, same as __pagevec_lru_add_fn, and lead the page place to
-* wrong lru list here. So relay on PageLocked to stop lruvec change
-* in mem_cgroup_move_account().
+* Serialize split tail pages in __split_huge_page_tail() by
+* lock_page(); Do TestClearPageMlocked/PageLRU sequence like
+* clear_page_mlock().
*/
- lruvec = lock_page_lruvec_irq(page);
-
- if (!TestClearPageMlocked(page)) {
+ if (!TestClearPageMlocked(page))
/* Potentially, PTE-mapped THP: do not skip the rest PTEs */
- nr_pages = 1;
- goto unlock_out;
- }
+ return 0;
nr_pages = thp_nr_pages(page);
__mod_zone_page_state(page_zone(page), NR_MLOCK, -nr_pages);
- if (__munlock_isolate_lru_page(page, lruvec, true)) {
- unlock_page_lruvec_irq(lruvec);
+ if (!isolate_lru_page(page))
__munlock_isolated_page(page);
- goto out;
- }
- __munlock_isolation_failed(page);
-
-unlock_out:
- unlock_page_lruvec_irq(lruvec);
+ else
+ __munlock_isolation_failed(page);
-out:
return nr_pages - 1;
}
@@ -305,6 +289,11 @@ static void __munlock_pagevec(struct pagevec *pvec, struct
zone *zone)
/* block memcg change in mem_cgroup_move_account */
lock_page_memcg(page);
+ /*
+* Serialize split tail pages in __split_huge_page_tail() which
+* might otherwise copy PageMlocked to part of the tail pages
+* before we clear it in the head page.
+*/
lruvec = relock_page_lruvec_irq(page, lruvec);
if (TestClearPageMlocked(page)) {
/*
--
1.8.3.1
