2022-02-24 12:50:34

by David Hildenbrand

Subject: [PATCH RFC 01/13] mm/rmap: fix missing swap_free() in try_to_unmap() after arch_unmap_one() failed

In case arch_unmap_one() fails, we already did a swap_duplicate(). let's
undo that properly via swap_free().

Fixes: ca827d55ebaa ("mm, swap: Add infrastructure for saving page metadata on swap")
Cc: Khalid Aziz <[email protected]>
Signed-off-by: David Hildenbrand <[email protected]>
---
mm/rmap.c | 1 +
1 file changed, 1 insertion(+)

diff --git a/mm/rmap.c b/mm/rmap.c
index 6a1e8c7f6213..f825aeef61ca 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -1625,6 +1625,7 @@ static bool try_to_unmap_one(struct page *page, struct vm_area_struct *vma,
break;
}
if (arch_unmap_one(mm, vma, address, pteval) < 0) {
+ swap_free(entry);
set_pte_at(mm, address, pvmw.pte, pteval);
ret = false;
page_vma_mapped_walk_done(&pvmw);
--
2.35.1

2022-02-24 16:50:51

by Khalid Aziz

Subject: Re: [PATCH RFC 01/13] mm/rmap: fix missing swap_free() in try_to_unmap() after arch_unmap_one() failed

On 2/24/22 05:26, David Hildenbrand wrote:
> In case arch_unmap_one() fails, we already did a swap_duplicate(). let's
> undo that properly via swap_free().
>
> Fixes: ca827d55ebaa ("mm, swap: Add infrastructure for saving page metadata on swap")
> Cc: Khalid Aziz <[email protected]>
> Signed-off-by: David Hildenbrand <[email protected]>
> ---
> mm/rmap.c | 1 +
> 1 file changed, 1 insertion(+)
>
> diff --git a/mm/rmap.c b/mm/rmap.c
> index 6a1e8c7f6213..f825aeef61ca 100644
> --- a/mm/rmap.c
> +++ b/mm/rmap.c
> @@ -1625,6 +1625,7 @@ static bool try_to_unmap_one(struct page *page, struct vm_area_struct *vma,
> break;
> }
> if (arch_unmap_one(mm, vma, address, pteval) < 0) {
> + swap_free(entry);
> set_pte_at(mm, address, pvmw.pte, pteval);
> ret = false;
> page_vma_mapped_walk_done(&pvmw);

That looks reasonable.

Reviewed-by: Khalid Aziz <[email protected]>

--
Khalid