memcgroup: fix typo in VM_BUG_ON()

PATCH In review Li Zefan 8 participants 21 messages Feb 18, 2008 7 messages not in the archive

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Li Zefan

author

2008-02-18 06:01 UTC #0 lore raw

PATCH 2/3 memcgroup: fix typo in VM_BUG_ON()

No need for VM_BUG_ON(pc), since 'pc' is the list entry. This should be VM_BUG_ON(page).

Signed-off-by Li Zefan <[email protected]>

Acked-by KAMEZAWA Hiroyuki <[email protected]>

---
 mm/memcontrol.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

mm/memcontrol.c +1 -1

index 6bded84..c2959ee 100644
@@ -534,7 +534,7 @@ unsigned long mem_cgroup_isolate_pages(unsigned long nr_to_scan,
 		if (scan >= nr_to_scan)
 			break;
 		page = pc->page;
-		VM_BUG_ON(!pc);
+		VM_BUG_ON(!page);
 
 		if (unlikely(!PageLRU(page)))
 			continue;

Signature · 1 line

1.5.4.rc3

A message that is not in the archive (sent off-list or not yet received): [email protected]

Balbir Singh

2008-02-18 06:14 UTC #2 lore raw

Quoted 5 lines · Li Zefan

No need for VM_BUG_ON(pc), since 'pc' is the list entry. This should be VM_BUG_ON(page).
Signed-off-by Li Zefan <[email protected]>
Acked-by KAMEZAWA Hiroyuki <[email protected]>

pc is of type page_cgroup and we use list_for_each_entry_safe_reverse. Not sure why we can't bug on pc.

Signature · 4 lines

	Warm Regards,
	Balbir Singh
	Linux Technology Center
	IBM, ISTL

YAMAMOTO Takashi

2008-02-18 06:39 UTC #3 lore raw

In reply to a message not in the archive

Quoted 14 lines

No need for VM_BUG_ON(pc), since 'pc' is the list entry. This should be VM_BUG_ON(page).
Signed-off-by Li Zefan <[email protected]>
Acked-by KAMEZAWA Hiroyuki <[email protected]>
---
 mm/memcontrol.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
mm/memcontrol.c +0 -0
index 6bded84..c2959ee 100644

mm/memcontrol.c unsigned long mem_cgroup_isolate_pages(unsigned long nr_to_scan, · line 537

Quoted 5 lines

mm/memcontrol.c +1 -1

@@ -534,7 +534,7 @@ unsigned long mem_cgroup_isolate_pages(unsigned long nr_to_scan,
 		if (scan >= nr_to_scan)
 			break;
 		page = pc->page;
-		VM_BUG_ON(!pc);
+		VM_BUG_ON(!page);

can't page be NULL here if mem_cgroup_uncharge clears pc->page behind us? ie. bug.

YAMAMOTO Takashi

Balbir Singh

2008-02-18 06:18 UTC #4 lore raw

In reply to Li Zefan

Quoted 5 lines · Li Zefan

No need for VM_BUG_ON(pc), since 'pc' is the list entry. This should be VM_BUG_ON(page).
Signed-off-by Li Zefan <[email protected]>
Acked-by KAMEZAWA Hiroyuki <[email protected]>

pc is of type page_cgroup and we use list_for_each_entry_safe_reverse. Not sure why we can't bug on pc.

Signature · 4 lines

	Warm Regards,
	Balbir Singh
	Linux Technology Center
	IBM, ISTL

YAMAMOTO Takashi

2008-02-18 06:22 UTC #5 lore raw

Quoted 9 lines

Quoted 5 lines · Li Zefan
No need for VM_BUG_ON(pc), since 'pc' is the list entry. This should be VM_BUG_ON(page).
Signed-off-by Li Zefan <[email protected]>
Acked-by KAMEZAWA Hiroyuki <[email protected]>
pc is of type page_cgroup and we use list_for_each_entry_safe_reverse. Not sure why we can't bug on pc.

pc is dereferenced before this VM_BUG_ON.

YAMAMOTO Takashi

Quoted 12 lines

Signature · 9 lines

-- 
	Warm Regards,
	Balbir Singh
	Linux Technology Center
	IBM, ISTL
_______________________________________________
Containers mailing list
[email protected]
https://lists.linux-foundation.org/mailman/listinfo/containers

A message that is not in the archive (sent off-list or not yet received): 20080218062209.DA59B1E3C58-Pcsii4f/[email protected]

Balbir Singh

2008-02-18 06:20 UTC #7 lore raw

Quoted 4 lines · YAMAMOTO Takashi

Quoted 4 lines
Quoted 3 lines · Li Zefan
No need for VM_BUG_ON(pc), since 'pc' is the list entry. This should be VM_BUG_ON(page).

Quoted 9 lines

Quoted 4 lines
Quoted 2 lines
Signed-off-by Li Zefan <[email protected]>
Acked-by KAMEZAWA Hiroyuki <[email protected]>
pc is of type page_cgroup and we use list_for_each_entry_safe_reverse. Not sure why we can't bug on pc.
pc is dereferenced before this VM_BUG_ON.
YAMAMOTO Takashi

OK, so the VM_BUG_ON needs to move to an earlier location. Agreed.

Signature · 4 lines

	Warm Regards,
	Balbir Singh
	Linux Technology Center
	IBM, ISTL

Balbir Singh

2008-02-18 06:24 UTC #8 lore raw

In reply to YAMAMOTO Takashi

Quoted 4 lines · YAMAMOTO Takashi

Quoted 4 lines
Quoted 3 lines · Li Zefan
No need for VM_BUG_ON(pc), since 'pc' is the list entry. This should be VM_BUG_ON(page).

Quoted 9 lines

Quoted 4 lines
Quoted 2 lines
Signed-off-by Li Zefan <[email protected]>
Acked-by KAMEZAWA Hiroyuki <[email protected]>
pc is of type page_cgroup and we use list_for_each_entry_safe_reverse. Not sure why we can't bug on pc.
pc is dereferenced before this VM_BUG_ON.
YAMAMOTO Takashi

OK, so the VM_BUG_ON needs to move to an earlier location. Agreed.

Signature · 4 lines

	Warm Regards,
	Balbir Singh
	Linux Technology Center
	IBM, ISTL

A message that is not in the archive (sent off-list or not yet received): 47B923C8.3090904-23VcF4HTsmIX0ybBhKVfKdBPR1lH4CV8@public.gmane.org

Li Zefan

2008-02-18 06:47 UTC #10 lore raw

Quoted 7 lines · Balbir Singh

Quoted 6 lines · YAMAMOTO Takashi
Quoted 6 lines
Quoted 5 lines · Li Zefan
No need for VM_BUG_ON(pc), since 'pc' is the list entry. This should be VM_BUG_ON(page).
Signed-off-by Li Zefan <[email protected]>
Acked-by KAMEZAWA Hiroyuki <[email protected]>

Quoted 9 lines

Quoted 6 lines
Quoted 2 lines
pc is of type page_cgroup and we use list_for_each_entry_safe_reverse. Not sure why we can't bug on pc.
pc is dereferenced before this VM_BUG_ON.
YAMAMOTO Takashi
OK, so the VM_BUG_ON needs to move to an earlier location. Agreed.

No, 'pc' has been dereferenced in list_for_each_entry_safe_reverse().

#define list_for_each_entry_safe_reverse(pos, n, head, member)		\
	for (pos = list_entry((head)->prev, typeof(*pos), member),	\
		n = list_entry(pos->member.prev, typeof(*pos), member);	\
                               ^^^^^^^^^^^
	     &pos->member != (head); 					\
              ^^^^^^^^^^^
	     pos = n, n = list_entry(n->member.prev, typeof(*n), member))

Li Zefan

author

2008-02-18 06:48 UTC #11 lore raw

In reply to Balbir Singh

Quoted 7 lines · Balbir Singh

Quoted 6 lines · YAMAMOTO Takashi
Quoted 6 lines
Quoted 5 lines · Li Zefan
No need for VM_BUG_ON(pc), since 'pc' is the list entry. This should be VM_BUG_ON(page).
Signed-off-by Li Zefan <[email protected]>
Acked-by KAMEZAWA Hiroyuki <[email protected]>

Quoted 9 lines

Quoted 6 lines
Quoted 2 lines
pc is of type page_cgroup and we use list_for_each_entry_safe_reverse. Not sure why we can't bug on pc.
pc is dereferenced before this VM_BUG_ON.
YAMAMOTO Takashi
OK, so the VM_BUG_ON needs to move to an earlier location. Agreed.

No, 'pc' has been dereferenced in list_for_each_entry_safe_reverse().

#define list_for_each_entry_safe_reverse(pos, n, head, member)		\
	for (pos = list_entry((head)->prev, typeof(*pos), member),	\
		n = list_entry(pos->member.prev, typeof(*pos), member);	\
                               ^^^^^^^^^^^
	     &pos->member != (head); 					\
              ^^^^^^^^^^^
	     pos = n, n = list_entry(n->member.prev, typeof(*n), member))

A message that is not in the archive (sent off-list or not yet received): [email protected]

Balbir Singh

2008-02-18 07:01 UTC #13 lore raw

Quoted 20 lines · Li Zefan

Quoted 7 lines · Balbir Singh
Quoted 6 lines · YAMAMOTO Takashi
Quoted 6 lines
Quoted 5 lines · Li Zefan
No need for VM_BUG_ON(pc), since 'pc' is the list entry. This should be VM_BUG_ON(page).
Signed-off-by Li Zefan <[email protected]>
Acked-by KAMEZAWA Hiroyuki <[email protected]>
Quoted 8 lines
Quoted 6 lines
Quoted 2 lines
pc is of type page_cgroup and we use list_for_each_entry_safe_reverse. Not sure why we can't bug on pc.
pc is dereferenced before this VM_BUG_ON.
YAMAMOTO Takashi
OK, so the VM_BUG_ON needs to move to an earlier location. Agreed.
No, 'pc' has been dereferenced in list_for_each_entry_safe_reverse().

Quoted 8 lines

#define list_for_each_entry_safe_reverse(pos, n, head, member)		\
	for (pos = list_entry((head)->prev, typeof(*pos), member),	\
		n = list_entry(pos->member.prev, typeof(*pos), member);	\
                               ^^^^^^^^^^^
	     &pos->member != (head); 					\
              ^^^^^^^^^^^
	     pos = n, n = list_entry(n->member.prev, typeof(*n), member))

Hmm.. We used to have a for loop with !list_empty() as a termination condition and VM_BUG_ON(!pc) is a spill over. With the new loop, VM_BUG_ON(!pc) does not make sense.

Signature · 4 lines

	Warm Regards,
	Balbir Singh
	Linux Technology Center
	IBM, ISTL

Balbir Singh

2008-02-18 07:05 UTC #14 lore raw

In reply to Li Zefan

Quoted 20 lines · Li Zefan

Quoted 7 lines · Balbir Singh
Quoted 6 lines · YAMAMOTO Takashi
Quoted 6 lines
Quoted 5 lines · Li Zefan
No need for VM_BUG_ON(pc), since 'pc' is the list entry. This should be VM_BUG_ON(page).
Signed-off-by Li Zefan <[email protected]>
Acked-by KAMEZAWA Hiroyuki <[email protected]>
Quoted 8 lines
Quoted 6 lines
Quoted 2 lines
pc is of type page_cgroup and we use list_for_each_entry_safe_reverse. Not sure why we can't bug on pc.
pc is dereferenced before this VM_BUG_ON.
YAMAMOTO Takashi
OK, so the VM_BUG_ON needs to move to an earlier location. Agreed.
No, 'pc' has been dereferenced in list_for_each_entry_safe_reverse().

Quoted 8 lines

#define list_for_each_entry_safe_reverse(pos, n, head, member)		\
	for (pos = list_entry((head)->prev, typeof(*pos), member),	\
		n = list_entry(pos->member.prev, typeof(*pos), member);	\
                               ^^^^^^^^^^^
	     &pos->member != (head); 					\
              ^^^^^^^^^^^
	     pos = n, n = list_entry(n->member.prev, typeof(*n), member))

Hmm.. We used to have a for loop with !list_empty() as a termination condition and VM_BUG_ON(!pc) is a spill over. With the new loop, VM_BUG_ON(!pc) does not make sense.

Signature · 4 lines

	Warm Regards,
	Balbir Singh
	Linux Technology Center
	IBM, ISTL

A message that is not in the archive (sent off-list or not yet received): 47B92D47.2050008-23VcF4HTsmIX0ybBhKVfKdBPR1lH4CV8@public.gmane.org

Li Zefan

2008-02-18 07:14 UTC #16 lore raw

Quoted 29 lines · Balbir Singh

Quoted 19 lines · Li Zefan
Quoted 7 lines · Balbir Singh
Quoted 6 lines · YAMAMOTO Takashi
Quoted 6 lines
Quoted 5 lines · Li Zefan
No need for VM_BUG_ON(pc), since 'pc' is the list entry. This should be VM_BUG_ON(page).
Signed-off-by Li Zefan <[email protected]>
Acked-by KAMEZAWA Hiroyuki <[email protected]>
Quoted 8 lines
Quoted 6 lines
Quoted 2 lines
pc is of type page_cgroup and we use list_for_each_entry_safe_reverse. Not sure why we can't bug on pc.
pc is dereferenced before this VM_BUG_ON.
YAMAMOTO Takashi
OK, so the VM_BUG_ON needs to move to an earlier location. Agreed.
No, 'pc' has been dereferenced in list_for_each_entry_safe_reverse().
Quoted 8 lines
#define list_for_each_entry_safe_reverse(pos, n, head, member)		\
	for (pos = list_entry((head)->prev, typeof(*pos), member),	\
		n = list_entry(pos->member.prev, typeof(*pos), member);	\
                               ^^^^^^^^^^^
	     &pos->member != (head); 					\
              ^^^^^^^^^^^
	     pos = n, n = list_entry(n->member.prev, typeof(*n), member))

Quoted 5 lines

Hmm.. We used to have a for loop with !list_empty() as a termination condition and VM_BUG_ON(!pc) is a spill over. With the new loop, VM_BUG_ON(!pc) does not make sense.

I see, and I'll post a new patch to just remove it.

Li Zefan

2008-02-18 07:34 UTC #17 lore raw

PATCH 1/1 memcgroup: remove a useless VM_BUG_ON()

In reply to a message not in the archive

Remove this VM_BUG_ON(), as Balbir stated:

We used to have a for loop with !list_empty() as a termination condition and VM_BUG_ON(!pc) is a spill over. With the new loop, VM_BUG_ON(!pc) does not make sense.

Signed-off-by Li Zefan <[email protected]>

---
 mm/memcontrol.c |    1 -
 1 files changed, 0 insertions(+), 1 deletions(-)

mm/memcontrol.c +0 -1

index 718acf8..631002d 100644
@@ -534,7 +534,6 @@ unsigned long mem_cgroup_isolate_pages(unsigned long nr_to_scan,
 		if (scan >= nr_to_scan)
 			break;
 		page = pc->page;
-		VM_BUG_ON(!pc);
 
 		if (unlikely(!PageLRU(page)))
 			continue;

Signature · 1 line

1.5.4.rc3

Li Zefan

author

2008-02-18 07:16 UTC #18 lore raw

In reply to Balbir Singh

Quoted 29 lines · Balbir Singh

Quoted 19 lines · Li Zefan
Quoted 7 lines · Balbir Singh
Quoted 6 lines · YAMAMOTO Takashi
Quoted 6 lines
Quoted 5 lines · Li Zefan
No need for VM_BUG_ON(pc), since 'pc' is the list entry. This should be VM_BUG_ON(page).
Signed-off-by Li Zefan <[email protected]>
Acked-by KAMEZAWA Hiroyuki <[email protected]>
Quoted 8 lines
Quoted 6 lines
Quoted 2 lines
pc is of type page_cgroup and we use list_for_each_entry_safe_reverse. Not sure why we can't bug on pc.
pc is dereferenced before this VM_BUG_ON.
YAMAMOTO Takashi
OK, so the VM_BUG_ON needs to move to an earlier location. Agreed.
No, 'pc' has been dereferenced in list_for_each_entry_safe_reverse().
Quoted 8 lines
#define list_for_each_entry_safe_reverse(pos, n, head, member)		\
	for (pos = list_entry((head)->prev, typeof(*pos), member),	\
		n = list_entry(pos->member.prev, typeof(*pos), member);	\
                               ^^^^^^^^^^^
	     &pos->member != (head); 					\
              ^^^^^^^^^^^
	     pos = n, n = list_entry(n->member.prev, typeof(*n), member))

Quoted 5 lines

Hmm.. We used to have a for loop with !list_empty() as a termination condition and VM_BUG_ON(!pc) is a spill over. With the new loop, VM_BUG_ON(!pc) does not make sense.

I see, and I'll post a new patch to just remove it.

Li Zefan

author

2008-02-18 07:36 UTC #19 lore raw

PATCH 1/1 memcgroup: remove a useless VM_BUG_ON()

In reply to Balbir Singh

Remove this VM_BUG_ON(), as Balbir stated:

We used to have a for loop with !list_empty() as a termination condition and VM_BUG_ON(!pc) is a spill over. With the new loop, VM_BUG_ON(!pc) does not make sense.

Signed-off-by Li Zefan <[email protected]>

---
 mm/memcontrol.c |    1 -
 1 files changed, 0 insertions(+), 1 deletions(-)

mm/memcontrol.c +0 -1

index 718acf8..631002d 100644
@@ -534,7 +534,6 @@ unsigned long mem_cgroup_isolate_pages(unsigned long nr_to_scan,
 		if (scan >= nr_to_scan)
 			break;
 		page = pc->page;
-		VM_BUG_ON(!pc);
 
 		if (unlikely(!PageLRU(page)))
 			continue;

Signature · 1 line

1.5.4.rc3

A message that is not in the archive (sent off-list or not yet received): [email protected]

Balbir Singh

Acked-by

2008-02-18 08:12 UTC #21 lore raw

Re: [PATCH] memcgroup: remove a useless VM_BUG_ON()

Quoted 16 lines · Li Zefan

Remove this VM_BUG_ON(), as Balbir stated:
We used to have a for loop with !list_empty() as a termination condition and VM_BUG_ON(!pc) is a spill over. With the new loop, VM_BUG_ON(!pc) does not make sense.
Signed-off-by Li Zefan <[email protected]>
---
 mm/memcontrol.c |    1 -
 1 files changed, 0 insertions(+), 1 deletions(-)
mm/memcontrol.c +0 -0
index 718acf8..631002d 100644

mm/memcontrol.c unsigned long mem_cgroup_isolate_pages(unsigned long nr_to_scan, · line 539

Quoted 7 lines

mm/memcontrol.c +0 -1

@@ -534,7 +534,6 @@ unsigned long mem_cgroup_isolate_pages(unsigned long nr_to_scan,
 		if (scan >= nr_to_scan)
 			break;
 		page = pc->page;
-		VM_BUG_ON(!pc);
 
 		if (unlikely(!PageLRU(page)))
 			continue;

This seems much better

Acked-by Balbir Singh <[email protected]>

Signature · 4 lines

	Warm Regards,
	Balbir Singh
	Linux Technology Center
	IBM, ISTL

KAMEZAWA Hiroyuki

Acked-by

2008-02-18 08:48 UTC #22 lore raw

Re: [PATCH] memcgroup: remove a useless VM_BUG_ON()

In reply to a message not in the archive

Quoted 26 lines · On Mon, 18 Feb 2008 15:34:48 +0800 Li Zefan…

Remove this VM_BUG_ON(), as Balbir stated:
We used to have a for loop with !list_empty() as a termination condition and VM_BUG_ON(!pc) is a spill over. With the new loop, VM_BUG_ON(!pc) does not make sense.
Signed-off-by Li Zefan <[email protected]>
---
 mm/memcontrol.c |    1 -
 1 files changed, 0 insertions(+), 1 deletions(-)
mm/memcontrol.c +0 -1
index 718acf8..631002d 100644
@@ -534,7 +534,6 @@ unsigned long mem_cgroup_isolate_pages(unsigned long nr_to_scan,
 		if (scan >= nr_to_scan)
 			break;
 		page = pc->page;
-		VM_BUG_ON(!pc);
 
 		if (unlikely(!PageLRU(page)))
 			continue;
Signature · 1 line
1.5.4.rc3

Acked-by KAMEZAWA Hiroyuki <[email protected]>

Thanks,
-Kame

Balbir Singh

Acked-by on v1 1/1

2008-02-18 08:16 UTC #23 lore raw

Re: [PATCH] memcgroup: remove a useless VM_BUG_ON()

In reply to Li Zefan

Quoted 16 lines · Li Zefan

Remove this VM_BUG_ON(), as Balbir stated:
We used to have a for loop with !list_empty() as a termination condition and VM_BUG_ON(!pc) is a spill over. With the new loop, VM_BUG_ON(!pc) does not make sense.
Signed-off-by Li Zefan <[email protected]>
---
 mm/memcontrol.c |    1 -
 1 files changed, 0 insertions(+), 1 deletions(-)
mm/memcontrol.c +0 -0
index 718acf8..631002d 100644

mm/memcontrol.c unsigned long mem_cgroup_isolate_pages(unsigned long nr_to_scan, · line 539

Quoted 7 lines

mm/memcontrol.c +0 -1

@@ -534,7 +534,6 @@ unsigned long mem_cgroup_isolate_pages(unsigned long nr_to_scan,
 		if (scan >= nr_to_scan)
 			break;
 		page = pc->page;
-		VM_BUG_ON(!pc);
 
 		if (unlikely(!PageLRU(page)))
 			continue;

This seems much better

Acked-by Balbir Singh <[email protected]>

Signature · 4 lines

	Warm Regards,
	Balbir Singh
	Linux Technology Center
	IBM, ISTL

KAMEZAWA Hiroyuki

Acked-by on v1 1/1

2008-02-18 08:46 UTC #24 lore raw

Re: [PATCH] memcgroup: remove a useless VM_BUG_ON()

In reply to Li Zefan

Quoted 26 lines · On Mon, 18 Feb 2008 15:34:48 +0800 Li Zefan <[email protected]> wrote:

Remove this VM_BUG_ON(), as Balbir stated:
We used to have a for loop with !list_empty() as a termination condition and VM_BUG_ON(!pc) is a spill over. With the new loop, VM_BUG_ON(!pc) does not make sense.
Signed-off-by Li Zefan <[email protected]>
---
 mm/memcontrol.c |    1 -
 1 files changed, 0 insertions(+), 1 deletions(-)
mm/memcontrol.c +0 -1
index 718acf8..631002d 100644
@@ -534,7 +534,6 @@ unsigned long mem_cgroup_isolate_pages(unsigned long nr_to_scan,
 		if (scan >= nr_to_scan)
 			break;
 		page = pc->page;
-		VM_BUG_ON(!pc);
 
 		if (unlikely(!PageLRU(page)))
 			continue;
Signature · 1 line
1.5.4.rc3

Acked-by KAMEZAWA Hiroyuki <[email protected]>

Thanks,
-Kame

A message that is not in the archive (sent off-list or not yet received): 47B9223C.9020106-23VcF4HTsmIX0ybBhKVfKdBPR1lH4CV8@public.gmane.org

YAMAMOTO Takashi

2008-02-18 06:22 UTC #26 lore raw

Quoted 9 lines

Quoted 5 lines · Li Zefan
No need for VM_BUG_ON(pc), since 'pc' is the list entry. This should be VM_BUG_ON(page).
Signed-off-by Li Zefan <[email protected]>
Acked-by KAMEZAWA Hiroyuki <[email protected]>
pc is of type page_cgroup and we use list_for_each_entry_safe_reverse. Not sure why we can't bug on pc.

pc is dereferenced before this VM_BUG_ON.

YAMAMOTO Takashi

Quoted 12 lines

Signature · 9 lines

-- 
	Warm Regards,
	Balbir Singh
	Linux Technology Center
	IBM, ISTL
_______________________________________________
Containers mailing list
Containers-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org
https://lists.linux-foundation.org/mailman/listinfo/containers

YAMAMOTO Takashi

2008-02-18 06:40 UTC #27 lore raw

In reply to Li Zefan

Quoted 14 lines

No need for VM_BUG_ON(pc), since 'pc' is the list entry. This should be VM_BUG_ON(page).
Signed-off-by Li Zefan <[email protected]>
Acked-by KAMEZAWA Hiroyuki <[email protected]>
---
 mm/memcontrol.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
mm/memcontrol.c +0 -0
index 6bded84..c2959ee 100644

mm/memcontrol.c unsigned long mem_cgroup_isolate_pages(unsigned long nr_to_scan, · line 537

Quoted 5 lines

mm/memcontrol.c +1 -1

@@ -534,7 +534,7 @@ unsigned long mem_cgroup_isolate_pages(unsigned long nr_to_scan,
 		if (scan >= nr_to_scan)
 			break;
 		page = pc->page;
-		VM_BUG_ON(!pc);
+		VM_BUG_ON(!page);

can't page be NULL here if mem_cgroup_uncharge clears pc->page behind us? ie. bug.

YAMAMOTO Takashi