Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > linux.kernel > #1687144 > unrolled thread

[PATCH] zsmalloc: zs_page_migrate: not check inuse if migrate_mode is not MIGRATE_ASYNC

Started byHui Zhu <zhuhui@xiaomi.com>
First post2017-07-14 10:10 +0200
Last post2017-07-17 08:10 +0200
Articles 2 — 2 participants

Back to article view | Back to linux.kernel

Contents

  [PATCH] zsmalloc: zs_page_migrate: not check inuse if migrate_mode is not MIGRATE_ASYNC Hui Zhu <zhuhui@xiaomi.com> - 2017-07-14 10:10 +0200
    Re: [PATCH] zsmalloc: zs_page_migrate: not check inuse if  migrate_mode is not MIGRATE_ASYNC Minchan Kim <minchan@kernel.org> - 2017-07-17 08:10 +0200

#1687144 — [PATCH] zsmalloc: zs_page_migrate: not check inuse if migrate_mode is not MIGRATE_ASYNC

FromHui Zhu <zhuhui@xiaomi.com>
Date2017-07-14 10:10 +0200
Subject[PATCH] zsmalloc: zs_page_migrate: not check inuse if migrate_mode is not MIGRATE_ASYNC
Message-ID<u33PI-El-29@gated-at.bofh.it>
Got some -EBUSY from zs_page_migrate that will make migration
slow (retry) or fail (zs_page_putback will schedule_work free_work,
but it cannot ensure the success).

And I didn't find anything that make zs_page_migrate cannot work with
a ZS_EMPTY zspage.
So make the patch to not check inuse if migrate_mode is not
MIGRATE_ASYNC.

Signed-off-by: Hui Zhu <zhuhui@xiaomi.com>
---
 mm/zsmalloc.c | 66 +++++++++++++++++++++++++++++++++--------------------------
 1 file changed, 37 insertions(+), 29 deletions(-)

diff --git a/mm/zsmalloc.c b/mm/zsmalloc.c
index d41edd2..c298e5c 100644
--- a/mm/zsmalloc.c
+++ b/mm/zsmalloc.c
@@ -1982,6 +1982,7 @@ int zs_page_migrate(struct address_space *mapping, struct page *newpage,
 	unsigned long old_obj, new_obj;
 	unsigned int obj_idx;
 	int ret = -EAGAIN;
+	int inuse;
 
 	VM_BUG_ON_PAGE(!PageMovable(page), page);
 	VM_BUG_ON_PAGE(!PageIsolated(page), page);
@@ -1996,21 +1997,24 @@ int zs_page_migrate(struct address_space *mapping, struct page *newpage,
 	offset = get_first_obj_offset(page);
 
 	spin_lock(&class->lock);
-	if (!get_zspage_inuse(zspage)) {
+	inuse = get_zspage_inuse(zspage);
+	if (mode == MIGRATE_ASYNC && !inuse) {
 		ret = -EBUSY;
 		goto unlock_class;
 	}
 
 	pos = offset;
 	s_addr = kmap_atomic(page);
-	while (pos < PAGE_SIZE) {
-		head = obj_to_head(page, s_addr + pos);
-		if (head & OBJ_ALLOCATED_TAG) {
-			handle = head & ~OBJ_ALLOCATED_TAG;
-			if (!trypin_tag(handle))
-				goto unpin_objects;
+	if (inuse) {
+		while (pos < PAGE_SIZE) {
+			head = obj_to_head(page, s_addr + pos);
+			if (head & OBJ_ALLOCATED_TAG) {
+				handle = head & ~OBJ_ALLOCATED_TAG;
+				if (!trypin_tag(handle))
+					goto unpin_objects;
+			}
+			pos += class->size;
 		}
-		pos += class->size;
 	}
 
 	/*
@@ -2020,20 +2024,22 @@ int zs_page_migrate(struct address_space *mapping, struct page *newpage,
 	memcpy(d_addr, s_addr, PAGE_SIZE);
 	kunmap_atomic(d_addr);
 
-	for (addr = s_addr + offset; addr < s_addr + pos;
-					addr += class->size) {
-		head = obj_to_head(page, addr);
-		if (head & OBJ_ALLOCATED_TAG) {
-			handle = head & ~OBJ_ALLOCATED_TAG;
-			if (!testpin_tag(handle))
-				BUG();
-
-			old_obj = handle_to_obj(handle);
-			obj_to_location(old_obj, &dummy, &obj_idx);
-			new_obj = (unsigned long)location_to_obj(newpage,
-								obj_idx);
-			new_obj |= BIT(HANDLE_PIN_BIT);
-			record_obj(handle, new_obj);
+	if (inuse) {
+		for (addr = s_addr + offset; addr < s_addr + pos;
+						addr += class->size) {
+			head = obj_to_head(page, addr);
+			if (head & OBJ_ALLOCATED_TAG) {
+				handle = head & ~OBJ_ALLOCATED_TAG;
+				if (!testpin_tag(handle))
+					BUG();
+
+				old_obj = handle_to_obj(handle);
+				obj_to_location(old_obj, &dummy, &obj_idx);
+				new_obj = (unsigned long)
+					location_to_obj(newpage, obj_idx);
+				new_obj |= BIT(HANDLE_PIN_BIT);
+				record_obj(handle, new_obj);
+			}
 		}
 	}
 
@@ -2055,14 +2061,16 @@ int zs_page_migrate(struct address_space *mapping, struct page *newpage,
 
 	ret = MIGRATEPAGE_SUCCESS;
 unpin_objects:
-	for (addr = s_addr + offset; addr < s_addr + pos;
+	if (inuse) {
+		for (addr = s_addr + offset; addr < s_addr + pos;
 						addr += class->size) {
-		head = obj_to_head(page, addr);
-		if (head & OBJ_ALLOCATED_TAG) {
-			handle = head & ~OBJ_ALLOCATED_TAG;
-			if (!testpin_tag(handle))
-				BUG();
-			unpin_tag(handle);
+			head = obj_to_head(page, addr);
+			if (head & OBJ_ALLOCATED_TAG) {
+				handle = head & ~OBJ_ALLOCATED_TAG;
+				if (!testpin_tag(handle))
+					BUG();
+				unpin_tag(handle);
+			}
 		}
 	}
 	kunmap_atomic(s_addr);
-- 
1.9.1

[toc] | [next] | [standalone]

#1688675 — Re: [PATCH] zsmalloc: zs_page_migrate: not check inuse if migrate_mode is not MIGRATE_ASYNC

FromMinchan Kim <minchan@kernel.org>
Date2017-07-17 08:10 +0200
SubjectRe: [PATCH] zsmalloc: zs_page_migrate: not check inuse if migrate_mode is not MIGRATE_ASYNC
Message-ID<u47od-1fK-1@gated-at.bofh.it>
In reply to#1687144
Hello Hui,

On Fri, Jul 14, 2017 at 03:51:07PM +0800, Hui Zhu wrote:
> Got some -EBUSY from zs_page_migrate that will make migration
> slow (retry) or fail (zs_page_putback will schedule_work free_work,
> but it cannot ensure the success).

I think EAGAIN(migration retrial) is better than EBUSY(bailout) because
expectation is that zsmalloc will release the empty zs_page soon so
at next retrial, it will be succeeded.
About schedule_work, as you said, we don't make sure when it happens but
I believe it will happen in a migration iteration most of case.
How often do you see that case?

> 
> And I didn't find anything that make zs_page_migrate cannot work with
> a ZS_EMPTY zspage.
> So make the patch to not check inuse if migrate_mode is not
> MIGRATE_ASYNC.

At a first glance, I think it work but the question is that it a same problem
ith schedule_work of zs_page_putback. IOW, Until the work is done, compaction
cannot succeed. Do you have any number before and after?

Thanks.

> 
> Signed-off-by: Hui Zhu <zhuhui@xiaomi.com>
> ---
>  mm/zsmalloc.c | 66 +++++++++++++++++++++++++++++++++--------------------------
>  1 file changed, 37 insertions(+), 29 deletions(-)
> 
> diff --git a/mm/zsmalloc.c b/mm/zsmalloc.c
> index d41edd2..c298e5c 100644
> --- a/mm/zsmalloc.c
> +++ b/mm/zsmalloc.c
> @@ -1982,6 +1982,7 @@ int zs_page_migrate(struct address_space *mapping, struct page *newpage,
>  	unsigned long old_obj, new_obj;
>  	unsigned int obj_idx;
>  	int ret = -EAGAIN;
> +	int inuse;
>  
>  	VM_BUG_ON_PAGE(!PageMovable(page), page);
>  	VM_BUG_ON_PAGE(!PageIsolated(page), page);
> @@ -1996,21 +1997,24 @@ int zs_page_migrate(struct address_space *mapping, struct page *newpage,
>  	offset = get_first_obj_offset(page);
>  
>  	spin_lock(&class->lock);
> -	if (!get_zspage_inuse(zspage)) {
> +	inuse = get_zspage_inuse(zspage);
> +	if (mode == MIGRATE_ASYNC && !inuse) {
>  		ret = -EBUSY;
>  		goto unlock_class;
>  	}
>  
>  	pos = offset;
>  	s_addr = kmap_atomic(page);
> -	while (pos < PAGE_SIZE) {
> -		head = obj_to_head(page, s_addr + pos);
> -		if (head & OBJ_ALLOCATED_TAG) {
> -			handle = head & ~OBJ_ALLOCATED_TAG;
> -			if (!trypin_tag(handle))
> -				goto unpin_objects;
> +	if (inuse) {
> +		while (pos < PAGE_SIZE) {
> +			head = obj_to_head(page, s_addr + pos);
> +			if (head & OBJ_ALLOCATED_TAG) {
> +				handle = head & ~OBJ_ALLOCATED_TAG;
> +				if (!trypin_tag(handle))
> +					goto unpin_objects;
> +			}
> +			pos += class->size;
>  		}
> -		pos += class->size;
>  	}
>  
>  	/*
> @@ -2020,20 +2024,22 @@ int zs_page_migrate(struct address_space *mapping, struct page *newpage,
>  	memcpy(d_addr, s_addr, PAGE_SIZE);
>  	kunmap_atomic(d_addr);
>  
> -	for (addr = s_addr + offset; addr < s_addr + pos;
> -					addr += class->size) {
> -		head = obj_to_head(page, addr);
> -		if (head & OBJ_ALLOCATED_TAG) {
> -			handle = head & ~OBJ_ALLOCATED_TAG;
> -			if (!testpin_tag(handle))
> -				BUG();
> -
> -			old_obj = handle_to_obj(handle);
> -			obj_to_location(old_obj, &dummy, &obj_idx);
> -			new_obj = (unsigned long)location_to_obj(newpage,
> -								obj_idx);
> -			new_obj |= BIT(HANDLE_PIN_BIT);
> -			record_obj(handle, new_obj);
> +	if (inuse) {
> +		for (addr = s_addr + offset; addr < s_addr + pos;
> +						addr += class->size) {
> +			head = obj_to_head(page, addr);
> +			if (head & OBJ_ALLOCATED_TAG) {
> +				handle = head & ~OBJ_ALLOCATED_TAG;
> +				if (!testpin_tag(handle))
> +					BUG();
> +
> +				old_obj = handle_to_obj(handle);
> +				obj_to_location(old_obj, &dummy, &obj_idx);
> +				new_obj = (unsigned long)
> +					location_to_obj(newpage, obj_idx);
> +				new_obj |= BIT(HANDLE_PIN_BIT);
> +				record_obj(handle, new_obj);
> +			}
>  		}
>  	}
>  
> @@ -2055,14 +2061,16 @@ int zs_page_migrate(struct address_space *mapping, struct page *newpage,
>  
>  	ret = MIGRATEPAGE_SUCCESS;
>  unpin_objects:
> -	for (addr = s_addr + offset; addr < s_addr + pos;
> +	if (inuse) {
> +		for (addr = s_addr + offset; addr < s_addr + pos;
>  						addr += class->size) {
> -		head = obj_to_head(page, addr);
> -		if (head & OBJ_ALLOCATED_TAG) {
> -			handle = head & ~OBJ_ALLOCATED_TAG;
> -			if (!testpin_tag(handle))
> -				BUG();
> -			unpin_tag(handle);
> +			head = obj_to_head(page, addr);
> +			if (head & OBJ_ALLOCATED_TAG) {
> +				handle = head & ~OBJ_ALLOCATED_TAG;
> +				if (!testpin_tag(handle))
> +					BUG();
> +				unpin_tag(handle);
> +			}
>  		}
>  	}
>  	kunmap_atomic(s_addr);
> -- 
> 1.9.1
> 
> --
> To unsubscribe, send a message with 'unsubscribe linux-mm' in
> the body to majordomo@kvack.org.  For more info on Linux MM,
> see: http://www.linux-mm.org/ .
> Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>

[toc] | [prev] | [standalone]

Back to top | Article view | linux.kernel

csiph-web