[PATCH] mm: mglru: fix stale batch updates after memcg reparenting

[PATCH] mm: mglru: fix stale batch updates after memcg reparenting

[Qi Zheng]

From: Qi Zheng <zhengqi.arch@bytedance.com>

The mglru page table walker batches per-generation size deltas in
walk->nr_pages while walking page tables without holding the lruvec lock.
The reset_batch_size() later folds those deltas into walk->lruvec under
the lruvec lock.

The page table walker can run concurrently with the memcg reparenting path
as follows:

CPU0                           CPU1
====                           ====

walk_mm
--> walk_page_range
    --> update_batch_size
        --> walk->nr_pages += delta

                              mem_cgroup_css_offline
                              --> memcg_reparent_objcgs
                                  --> lock lruvec
                                      lru_gen_reparent_memcg
                                      --> reparent child folios to parent
                                      unlock lruvec

    lock lruvec
    reset_batch_size
    --> child lrugen->nr_pages += delta

This can trigger the following warning:

WARNING: mm/vmscan.c:5867 at lru_gen_exit_memcg+0x26f/0x300
RIP: 0010:lru_gen_exit_memcg+0x26f/0x300 mm/vmscan.c:5867
Call Trace:
  <TASK>
  mem_cgroup_free mm/memcontrol.c:3972 [inline]
  mem_cgroup_css_free+0x76/0xb0 mm/memcontrol.c:4241
  css_free_rwork_fn+0x125/0x1260 kernel/cgroup/cgroup.c:5575
  process_one_work+0xa0d/0x1c30 kernel/workqueue.c:3314
  process_scheduled_works kernel/workqueue.c:3397 [inline]
  worker_thread+0x645/0xe80 kernel/workqueue.c:3478
  kthread+0x367/0x480 kernel/kthread.c:436
  ret_from_fork+0x72b/0xd50 arch/x86/kernel/process.c:158
  ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
  </TASK>

To fix it, add lrugen->reparented to remember the new owner of a
reparented lruvec, and make reset_batch_size() charge pending deltas to
that owner.

Reported-by: Peiyang He <peiyang_he@smail.nju.edu.cn>
Closes: https://lore.kernel.org/all/5A9E929D82717101+12fcf643-efb8-4b9a-a53a-1e28cc894f0b@smail.nju.edu.cn
Fixes: f304652609ea ("mm: vmscan: prepare for reparenting MGLRU folios")
Cc: <stable@vger.kernel.org>
Signed-off-by: Qi Zheng <zhengqi.arch@bytedance.com>
---
 include/linux/mmzone.h |  4 ++++
 mm/vmscan.c            | 43 +++++++++++++++++++++++++++++++++++-------
 2 files changed, 40 insertions(+), 7 deletions(-)

diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
index ca2712187147..0d572db2ef64 100644
--- a/include/linux/mmzone.h
+++ b/include/linux/mmzone.h
@@ -584,6 +584,10 @@ struct lru_gen_folio {
 	u8 gen;
 	/* the list segment this lru_gen_folio belongs to */
 	u8 seg;
+#ifdef CONFIG_MEMCG
+	/* the lruvec this lruvec has been reparented to */
+	struct lruvec *reparented;
+#endif
 	/* per-node lru_gen_folio list for global reclaim */
 	struct hlist_nulls_node list;
 };
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 35c3bb15ae96..64362cbed814 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -3262,10 +3262,37 @@ static void update_batch_size(struct lru_gen_mm_walk *walk, struct folio *folio,
 	walk->nr_pages[new_gen][type][zone] += delta;
 }
 
+#ifdef CONFIG_MEMCG
+static struct lruvec *lock_batch_lruvec(struct lruvec *lruvec)
+{
+	struct lruvec *reparented;
+
+	for (;;) {
+		lruvec_lock_irq(lruvec);
+
+		reparented = lruvec->lrugen.reparented;
+		if (!reparented)
+			break;
+
+		lruvec_unlock_irq(lruvec);
+		lruvec = reparented;
+	}
+
+	return lruvec;
+}
+#else
+static struct lruvec *lock_batch_lruvec(struct lruvec *lruvec)
+{
+	lruvec_lock_irq(lruvec);
+
+	return lruvec;
+}
+#endif
+
 static void reset_batch_size(struct lru_gen_mm_walk *walk)
 {
 	int gen, type, zone;
-	struct lruvec *lruvec = walk->lruvec;
+	struct lruvec *lruvec = lock_batch_lruvec(walk->lruvec);
 	struct lru_gen_folio *lrugen = &lruvec->lrugen;
 
 	walk->batched = 0;
@@ -3285,6 +3312,8 @@ static void reset_batch_size(struct lru_gen_mm_walk *walk)
 			lru += LRU_ACTIVE;
 		__update_lru_size(lruvec, lru, zone, delta);
 	}
+
+	lruvec_unlock_irq(lruvec);
 }
 
 static int should_skip_vma(unsigned long start, unsigned long end, struct mm_walk *args)
@@ -3779,11 +3808,8 @@ static void walk_mm(struct mm_struct *mm, struct lru_gen_mm_walk *walk)
 			mmap_read_unlock(mm);
 		}
 
-		if (walk->batched) {
-			lruvec_lock_irq(lruvec);
+		if (walk->batched)
 			reset_batch_size(walk);
-			lruvec_unlock_irq(lruvec);
-		}
 
 		cond_resched();
 	} while (err == -EAGAIN);
@@ -4563,6 +4589,8 @@ void lru_gen_reparent_memcg(struct mem_cgroup *memcg, struct mem_cgroup *parent,
 			mem_cgroup_update_lru_size(parent_lruvec, lru, zid, size);
 		}
 	}
+
+	child_lruvec->lrugen.reparented = parent_lruvec;
 }
 
 #endif /* CONFIG_MEMCG */
@@ -4867,9 +4895,7 @@ static int evict_folios(unsigned long nr_to_scan, struct lruvec *lruvec,
 	walk = current->reclaim_state->mm_walk;
 	if (walk && walk->batched) {
 		walk->lruvec = lruvec;
-		lruvec_lock_irq(lruvec);
 		reset_batch_size(walk);
-		lruvec_unlock_irq(lruvec);
 	}
 
 	mod_lruvec_state(lruvec, PGDEMOTE_KSWAPD + reclaimer_offset(sc),
@@ -5784,6 +5810,9 @@ void lru_gen_init_lruvec(struct lruvec *lruvec)
 
 	lrugen->max_seq = MIN_NR_GENS + 1;
 	lrugen->enabled = lru_gen_enabled();
+#ifdef CONFIG_MEMCG
+	lrugen->reparented = NULL;
+#endif
 
 	for (i = 0; i <= MIN_NR_GENS + 1; i++)
 		lrugen->timestamps[i] = jiffies;
-- 
2.54.0

Re: [PATCH] mm: mglru: fix stale batch updates after memcg reparenting

[Peiyang He]

Hi Qi,

Thanks for confirming this bug and proposing the patch. The fix I previously proposed was indeed incorrect. I have applied your patch and tested it using the PoC script that previously triggered the warning; no warning is observed anymore.

Best,
Peiyang

On 2026/6/22 15:37, Qi Zheng wrote:
> From: Qi Zheng <zhengqi.arch@bytedance.com>
> 
> The mglru page table walker batches per-generation size deltas in
> walk->nr_pages while walking page tables without holding the lruvec lock.
> The reset_batch_size() later folds those deltas into walk->lruvec under
> the lruvec lock.
> 
> The page table walker can run concurrently with the memcg reparenting path
> as follows:
> 
> CPU0                           CPU1
> ====                           ====
> 
> walk_mm
> --> walk_page_range
>     --> update_batch_size
>         --> walk->nr_pages += delta
> 
>                               mem_cgroup_css_offline
>                               --> memcg_reparent_objcgs
>                                   --> lock lruvec
>                                       lru_gen_reparent_memcg
>                                       --> reparent child folios to parent
>                                       unlock lruvec
> 
>     lock lruvec
>     reset_batch_size
>     --> child lrugen->nr_pages += delta
> 
> This can trigger the following warning:
> 
> WARNING: mm/vmscan.c:5867 at lru_gen_exit_memcg+0x26f/0x300
> RIP: 0010:lru_gen_exit_memcg+0x26f/0x300 mm/vmscan.c:5867
> Call Trace:
>   <TASK>
>   mem_cgroup_free mm/memcontrol.c:3972 [inline]
>   mem_cgroup_css_free+0x76/0xb0 mm/memcontrol.c:4241
>   css_free_rwork_fn+0x125/0x1260 kernel/cgroup/cgroup.c:5575
>   process_one_work+0xa0d/0x1c30 kernel/workqueue.c:3314
>   process_scheduled_works kernel/workqueue.c:3397 [inline]
>   worker_thread+0x645/0xe80 kernel/workqueue.c:3478
>   kthread+0x367/0x480 kernel/kthread.c:436
>   ret_from_fork+0x72b/0xd50 arch/x86/kernel/process.c:158
>   ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
>   </TASK>
> 
> To fix it, add lrugen->reparented to remember the new owner of a
> reparented lruvec, and make reset_batch_size() charge pending deltas to
> that owner.
> 
> Reported-by: Peiyang He <peiyang_he@smail.nju.edu.cn>
> Closes: https://lore.kernel.org/all/5A9E929D82717101+12fcf643-efb8-4b9a-a53a-1e28cc894f0b@smail.nju.edu.cn
> Fixes: f304652609ea ("mm: vmscan: prepare for reparenting MGLRU folios")
> Cc: <stable@vger.kernel.org>
> Signed-off-by: Qi Zheng <zhengqi.arch@bytedance.com>
> ---
>  include/linux/mmzone.h |  4 ++++
>  mm/vmscan.c            | 43 +++++++++++++++++++++++++++++++++++-------
>  2 files changed, 40 insertions(+), 7 deletions(-)
> 
> diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
> index ca2712187147..0d572db2ef64 100644
> --- a/include/linux/mmzone.h
> +++ b/include/linux/mmzone.h
> @@ -584,6 +584,10 @@ struct lru_gen_folio {
>  	u8 gen;
>  	/* the list segment this lru_gen_folio belongs to */
>  	u8 seg;
> +#ifdef CONFIG_MEMCG
> +	/* the lruvec this lruvec has been reparented to */
> +	struct lruvec *reparented;
> +#endif
>  	/* per-node lru_gen_folio list for global reclaim */
>  	struct hlist_nulls_node list;
>  };
> diff --git a/mm/vmscan.c b/mm/vmscan.c
> index 35c3bb15ae96..64362cbed814 100644
> --- a/mm/vmscan.c
> +++ b/mm/vmscan.c
> @@ -3262,10 +3262,37 @@ static void update_batch_size(struct lru_gen_mm_walk *walk, struct folio *folio,
>  	walk->nr_pages[new_gen][type][zone] += delta;
>  }
>  
> +#ifdef CONFIG_MEMCG
> +static struct lruvec *lock_batch_lruvec(struct lruvec *lruvec)
> +{
> +	struct lruvec *reparented;
> +
> +	for (;;) {
> +		lruvec_lock_irq(lruvec);
> +
> +		reparented = lruvec->lrugen.reparented;
> +		if (!reparented)
> +			break;
> +
> +		lruvec_unlock_irq(lruvec);
> +		lruvec = reparented;
> +	}
> +
> +	return lruvec;
> +}
> +#else
> +static struct lruvec *lock_batch_lruvec(struct lruvec *lruvec)
> +{
> +	lruvec_lock_irq(lruvec);
> +
> +	return lruvec;
> +}
> +#endif
> +
>  static void reset_batch_size(struct lru_gen_mm_walk *walk)
>  {
>  	int gen, type, zone;
> -	struct lruvec *lruvec = walk->lruvec;
> +	struct lruvec *lruvec = lock_batch_lruvec(walk->lruvec);
>  	struct lru_gen_folio *lrugen = &lruvec->lrugen;
>  
>  	walk->batched = 0;
> @@ -3285,6 +3312,8 @@ static void reset_batch_size(struct lru_gen_mm_walk *walk)
>  			lru += LRU_ACTIVE;
>  		__update_lru_size(lruvec, lru, zone, delta);
>  	}
> +
> +	lruvec_unlock_irq(lruvec);
>  }
>  
>  static int should_skip_vma(unsigned long start, unsigned long end, struct mm_walk *args)
> @@ -3779,11 +3808,8 @@ static void walk_mm(struct mm_struct *mm, struct lru_gen_mm_walk *walk)
>  			mmap_read_unlock(mm);
>  		}
>  
> -		if (walk->batched) {
> -			lruvec_lock_irq(lruvec);
> +		if (walk->batched)
>  			reset_batch_size(walk);
> -			lruvec_unlock_irq(lruvec);
> -		}
>  
>  		cond_resched();
>  	} while (err == -EAGAIN);
> @@ -4563,6 +4589,8 @@ void lru_gen_reparent_memcg(struct mem_cgroup *memcg, struct mem_cgroup *parent,
>  			mem_cgroup_update_lru_size(parent_lruvec, lru, zid, size);
>  		}
>  	}
> +
> +	child_lruvec->lrugen.reparented = parent_lruvec;
>  }
>  
>  #endif /* CONFIG_MEMCG */
> @@ -4867,9 +4895,7 @@ static int evict_folios(unsigned long nr_to_scan, struct lruvec *lruvec,
>  	walk = current->reclaim_state->mm_walk;
>  	if (walk && walk->batched) {
>  		walk->lruvec = lruvec;
> -		lruvec_lock_irq(lruvec);
>  		reset_batch_size(walk);
> -		lruvec_unlock_irq(lruvec);
>  	}
>  
>  	mod_lruvec_state(lruvec, PGDEMOTE_KSWAPD + reclaimer_offset(sc),
> @@ -5784,6 +5810,9 @@ void lru_gen_init_lruvec(struct lruvec *lruvec)
>  
>  	lrugen->max_seq = MIN_NR_GENS + 1;
>  	lrugen->enabled = lru_gen_enabled();
> +#ifdef CONFIG_MEMCG
> +	lrugen->reparented = NULL;
> +#endif
>  
>  	for (i = 0; i <= MIN_NR_GENS + 1; i++)
>  		lrugen->timestamps[i] = jiffies;

Re: [PATCH] mm: mglru: fix stale batch updates after memcg reparenting

[Qi Zheng]

On 6/22/26 4:24 PM, Peiyang He wrote:
> Hi Qi,
> 
> Thanks for confirming this bug and proposing the patch. The fix I previously proposed was indeed incorrect. I have applied your patch and tested it using the PoC script that previously triggered the warning; no warning is observed anymore.

Good news.

Thanks for testing this!

Re: [PATCH] mm: mglru: fix stale batch updates after memcg reparenting

[Barry Song]

On Mon, Jun 22, 2026 at 3:38 PM Qi Zheng <qi.zheng@linux.dev> wrote:
>
> From: Qi Zheng <zhengqi.arch@bytedance.com>
>
> The mglru page table walker batches per-generation size deltas in
> walk->nr_pages while walking page tables without holding the lruvec lock.
> The reset_batch_size() later folds those deltas into walk->lruvec under
> the lruvec lock.
>
> The page table walker can run concurrently with the memcg reparenting path
> as follows:
>
> CPU0                           CPU1
> ====                           ====
>
> walk_mm
> --> walk_page_range
>     --> update_batch_size
>         --> walk->nr_pages += delta
>
>                               mem_cgroup_css_offline
>                               --> memcg_reparent_objcgs
>                                   --> lock lruvec
>                                       lru_gen_reparent_memcg
>                                       --> reparent child folios to parent
>                                       unlock lruvec
>
>     lock lruvec
>     reset_batch_size
>     --> child lrugen->nr_pages += delta
>
> This can trigger the following warning:
>
> WARNING: mm/vmscan.c:5867 at lru_gen_exit_memcg+0x26f/0x300
> RIP: 0010:lru_gen_exit_memcg+0x26f/0x300 mm/vmscan.c:5867

I can't find 5867; instead, I can find 5828:

VM_WARN_ON_ONCE(memchr_inv(lruvec->lrugen.nr_pages, 0,
  sizeof(lruvec->lrugen.nr_pages)));

Is this the warning?

> Call Trace:
>   <TASK>
>   mem_cgroup_free mm/memcontrol.c:3972 [inline]
>   mem_cgroup_css_free+0x76/0xb0 mm/memcontrol.c:4241
>   css_free_rwork_fn+0x125/0x1260 kernel/cgroup/cgroup.c:5575
>   process_one_work+0xa0d/0x1c30 kernel/workqueue.c:3314
>   process_scheduled_works kernel/workqueue.c:3397 [inline]
>   worker_thread+0x645/0xe80 kernel/workqueue.c:3478
>   kthread+0x367/0x480 kernel/kthread.c:436
>   ret_from_fork+0x72b/0xd50 arch/x86/kernel/process.c:158
>   ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
>   </TASK>
>
> To fix it, add lrugen->reparented to remember the new owner of a
> reparented lruvec, and make reset_batch_size() charge pending deltas to
> that owner.
>
> Reported-by: Peiyang He <peiyang_he@smail.nju.edu.cn>
> Closes: https://lore.kernel.org/all/5A9E929D82717101+12fcf643-efb8-4b9a-a53a-1e28cc894f0b@smail.nju.edu.cn
> Fixes: f304652609ea ("mm: vmscan: prepare for reparenting MGLRU folios")
> Cc: <stable@vger.kernel.org>
> Signed-off-by: Qi Zheng <zhengqi.arch@bytedance.com>

Looks reasonable to me.
Reviewed-by: Barry Song <baohua@kernel.org>

Re: [PATCH] mm: mglru: fix stale batch updates after memcg reparenting

[Qi Zheng]

Hi Barry,

On 6/23/26 6:52 AM, Barry Song wrote:
> On Mon, Jun 22, 2026 at 3:38 PM Qi Zheng <qi.zheng@linux.dev> wrote:
>>
>> From: Qi Zheng <zhengqi.arch@bytedance.com>
>>
>> The mglru page table walker batches per-generation size deltas in
>> walk->nr_pages while walking page tables without holding the lruvec lock.
>> The reset_batch_size() later folds those deltas into walk->lruvec under
>> the lruvec lock.
>>
>> The page table walker can run concurrently with the memcg reparenting path
>> as follows:
>>
>> CPU0                           CPU1
>> ====                           ====
>>
>> walk_mm
>> --> walk_page_range
>>      --> update_batch_size
>>          --> walk->nr_pages += delta
>>
>>                                mem_cgroup_css_offline
>>                                --> memcg_reparent_objcgs
>>                                    --> lock lruvec
>>                                        lru_gen_reparent_memcg
>>                                        --> reparent child folios to parent
>>                                        unlock lruvec
>>
>>      lock lruvec
>>      reset_batch_size
>>      --> child lrugen->nr_pages += delta
>>
>> This can trigger the following warning:
>>
>> WARNING: mm/vmscan.c:5867 at lru_gen_exit_memcg+0x26f/0x300
>> RIP: 0010:lru_gen_exit_memcg+0x26f/0x300 mm/vmscan.c:5867
> 
> I can't find 5867; instead, I can find 5828:
> 
> VM_WARN_ON_ONCE(memchr_inv(lruvec->lrugen.nr_pages, 0,
>    sizeof(lruvec->lrugen.nr_pages)));
> 
> Is this the warning?

Yes, I just copy-pasted the warning log from Peiyang's report.

Maybe the description should be changed to:

This will trigger the following warning in lru_gen_exit_memcg():

	VM_WARN_ON_ONCE(memchr_inv(lruvec->lrugen.nr_pages, 0,
					   sizeof(lruvec->lrugen.nr_pages)));

> 
>> Call Trace:
>>    <TASK>
>>    mem_cgroup_free mm/memcontrol.c:3972 [inline]
>>    mem_cgroup_css_free+0x76/0xb0 mm/memcontrol.c:4241
>>    css_free_rwork_fn+0x125/0x1260 kernel/cgroup/cgroup.c:5575
>>    process_one_work+0xa0d/0x1c30 kernel/workqueue.c:3314
>>    process_scheduled_works kernel/workqueue.c:3397 [inline]
>>    worker_thread+0x645/0xe80 kernel/workqueue.c:3478
>>    kthread+0x367/0x480 kernel/kthread.c:436
>>    ret_from_fork+0x72b/0xd50 arch/x86/kernel/process.c:158
>>    ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
>>    </TASK>
>>
>> To fix it, add lrugen->reparented to remember the new owner of a
>> reparented lruvec, and make reset_batch_size() charge pending deltas to
>> that owner.
>>
>> Reported-by: Peiyang He <peiyang_he@smail.nju.edu.cn>
>> Closes: https://lore.kernel.org/all/5A9E929D82717101+12fcf643-efb8-4b9a-a53a-1e28cc894f0b@smail.nju.edu.cn
>> Fixes: f304652609ea ("mm: vmscan: prepare for reparenting MGLRU folios")
>> Cc: <stable@vger.kernel.org>
>> Signed-off-by: Qi Zheng <zhengqi.arch@bytedance.com>
> 
> Looks reasonable to me.
> Reviewed-by: Barry Song <baohua@kernel.org>

Thanks!

Re: [PATCH] mm: mglru: fix stale batch updates after memcg reparenting

[Barry Song]

On Tue, Jun 23, 2026 at 9:58 AM Qi Zheng <qi.zheng@linux.dev> wrote:
>
> Hi Barry,
>
> On 6/23/26 6:52 AM, Barry Song wrote:
> > On Mon, Jun 22, 2026 at 3:38 PM Qi Zheng <qi.zheng@linux.dev> wrote:
> >>
> >> From: Qi Zheng <zhengqi.arch@bytedance.com>
> >>
> >> The mglru page table walker batches per-generation size deltas in
> >> walk->nr_pages while walking page tables without holding the lruvec lock.
> >> The reset_batch_size() later folds those deltas into walk->lruvec under
> >> the lruvec lock.
> >>
> >> The page table walker can run concurrently with the memcg reparenting path
> >> as follows:
> >>
> >> CPU0                           CPU1
> >> ====                           ====
> >>
> >> walk_mm
> >> --> walk_page_range
> >>      --> update_batch_size
> >>          --> walk->nr_pages += delta
> >>
> >>                                mem_cgroup_css_offline
> >>                                --> memcg_reparent_objcgs
> >>                                    --> lock lruvec
> >>                                        lru_gen_reparent_memcg
> >>                                        --> reparent child folios to parent
> >>                                        unlock lruvec
> >>
> >>      lock lruvec
> >>      reset_batch_size
> >>      --> child lrugen->nr_pages += delta
> >>
> >> This can trigger the following warning:
> >>
> >> WARNING: mm/vmscan.c:5867 at lru_gen_exit_memcg+0x26f/0x300
> >> RIP: 0010:lru_gen_exit_memcg+0x26f/0x300 mm/vmscan.c:5867
> >
> > I can't find 5867; instead, I can find 5828:
> >
> > VM_WARN_ON_ONCE(memchr_inv(lruvec->lrugen.nr_pages, 0,
> >    sizeof(lruvec->lrugen.nr_pages)));
> >
> > Is this the warning?
>
> Yes, I just copy-pasted the warning log from Peiyang's report.
>
> Maybe the description should be changed to:
>
> This will trigger the following warning in lru_gen_exit_memcg():
>
>         VM_WARN_ON_ONCE(memchr_inv(lruvec->lrugen.nr_pages, 0,
>                                            sizeof(lruvec->lrugen.nr_pages)));
>
> >

Yep. Can we update the v2 changelog accordingly?

Best Regards
Barry

Re: [PATCH] mm: mglru: fix stale batch updates after memcg reparenting

[Qi Zheng]

On 6/23/26 10:15 AM, Barry Song wrote:
> On Tue, Jun 23, 2026 at 9:58 AM Qi Zheng <qi.zheng@linux.dev> wrote:
>>

[...]

>>>>
>>>> WARNING: mm/vmscan.c:5867 at lru_gen_exit_memcg+0x26f/0x300
>>>> RIP: 0010:lru_gen_exit_memcg+0x26f/0x300 mm/vmscan.c:5867
>>>
>>> I can't find 5867; instead, I can find 5828:
>>>
>>> VM_WARN_ON_ONCE(memchr_inv(lruvec->lrugen.nr_pages, 0,
>>>     sizeof(lruvec->lrugen.nr_pages)));
>>>
>>> Is this the warning?
>>
>> Yes, I just copy-pasted the warning log from Peiyang's report.
>>
>> Maybe the description should be changed to:
>>
>> This will trigger the following warning in lru_gen_exit_memcg():
>>
>>          VM_WARN_ON_ONCE(memchr_inv(lruvec->lrugen.nr_pages, 0,
>>                                             sizeof(lruvec->lrugen.nr_pages)));
>>
>>>
> 
> Yep. Can we update the v2 changelog accordingly?

Sure, will do in v2.

Thanks,
Qi

> 
> Best Regards
> Barry