2024-05-24 00:36:10

by Yuanyuan Zhong

Subject: [PATCH] mm: /proc/pid/smaps_rollup: avoid skipping vma after getting mmap_lock again

After switching smaps_rollup to use VMA iterator, searching for next
entry is part of the condition expression of the do-while loop. So the
current VMA needs to be addressed before the continue statement.

Fixes: c4c84f06285e ("fs/proc/task_mmu: stop using linked list and highest_vm_end")
Signed-off-by: Yuanyuan Zhong <[email protected]>
Reviewed-by: Mohamed Khalfella <[email protected]>
---
fs/proc/task_mmu.c | 9 +++++++--
1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index e5a5f015ff03..f8d35f993fe5 100644
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -970,12 +970,17 @@ static int show_smaps_rollup(struct seq_file *m, void *v)
break;

/* Case 1 and 2 above */
- if (vma->vm_start >= last_vma_end)
+ if (vma->vm_start >= last_vma_end) {
+ smap_gather_stats(vma, &mss, 0);
+ last_vma_end = vma->vm_end;
continue;
+ }

/* Case 4 above */
- if (vma->vm_end > last_vma_end)
+ if (vma->vm_end > last_vma_end) {
smap_gather_stats(vma, &mss, last_vma_end);
+ last_vma_end = vma->vm_end;
+ }
}
} for_each_vma(vmi, vma);

--
2.34.1

2024-05-27 07:43:23

by David Hildenbrand

Subject: Re: [PATCH] mm: /proc/pid/smaps_rollup: avoid skipping vma after getting mmap_lock again

Am 23.05.24 um 20:35 schrieb Yuanyuan Zhong:
> After switching smaps_rollup to use VMA iterator, searching for next
> entry is part of the condition expression of the do-while loop. So the
> current VMA needs to be addressed before the continue statement.
>
> Fixes: c4c84f06285e ("fs/proc/task_mmu: stop using linked list and highest_vm_end")
> Signed-off-by: Yuanyuan Zhong <[email protected]>
> Reviewed-by: Mohamed Khalfella <[email protected]>
> ---
> fs/proc/task_mmu.c | 9 +++++++--
> 1 file changed, 7 insertions(+), 2 deletions(-)
>
> diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
> index e5a5f015ff03..f8d35f993fe5 100644
> --- a/fs/proc/task_mmu.c
> +++ b/fs/proc/task_mmu.c
> @@ -970,12 +970,17 @@ static int show_smaps_rollup(struct seq_file *m, void *v)
> break;
>
> /* Case 1 and 2 above */
> - if (vma->vm_start >= last_vma_end)
> + if (vma->vm_start >= last_vma_end) {
> + smap_gather_stats(vma, &mss, 0);
> + last_vma_end = vma->vm_end;
> continue;
> + }
>
> /* Case 4 above */
> - if (vma->vm_end > last_vma_end)
> + if (vma->vm_end > last_vma_end) {
> smap_gather_stats(vma, &mss, last_vma_end);
> + last_vma_end = vma->vm_end;
> + }
> }
> } for_each_vma(vmi, vma);
>

Looks correct to me. I guess getting a reproducer is rather tricky.

Acked-by: David Hildenbrand <[email protected]>

--
Thanks,

David / dhildenb