On 10/13/23 21:58, Naoya Horiguchi wrote:
> On Tue, Sep 05, 2023 at 02:44:00PM -0700, Mike Kravetz wrote:
> >
> > Fixes: f41f2ed43ca5 ("mm: hugetlb: free the vmemmap pages associated with each HugeTLB page")
> > Signed-off-by: Mike Kravetz <mike.kravetz@xxxxxxxxxx>
>
> I saw that VM_WARN_ON_ONCE() in hugetlb_vmemmap_restore is triggered when
> memory_failure() is called on a free hugetlb page with vmemmap optimization
> disabled (the warning is not triggered if vmemmap optimization is enabled).
> I think that we need check folio_test_hugetlb() before dissolve_free_huge_page()
> calls hugetlb_vmemmap_restore_folio().
>
> Could you consider adding some diff like below?
>
> diff --git a/mm/hugetlb.c b/mm/hugetlb.c
> --- a/mm/hugetlb.c
> +++ b/mm/hugetlb.c
> @@ -2312,15 +2312,16 @@ int dissolve_free_huge_page(struct page *page)
> * Attempt to allocate vmemmmap here so that we can take
> * appropriate action on failure.
> */
> - rc = hugetlb_vmemmap_restore_folio(h, folio);
> - if (!rc) {
> - update_and_free_hugetlb_folio(h, folio, false);
> - } else {
> - spin_lock_irq(&hugetlb_lock);
> - add_hugetlb_folio(h, folio, false);
> - h->max_huge_pages++;
> - spin_unlock_irq(&hugetlb_lock);
> + if (folio_test_hugetlb(folio)) {
> + rc = hugetlb_vmemmap_restore_folio(h, folio);
> + if (rc) {
> + spin_lock_irq(&hugetlb_lock);
> + add_hugetlb_folio(h, folio, false);
> + h->max_huge_pages++;
> + goto out;
> + }
> }
> + update_and_free_hugetlb_folio(h, folio, false);
>
> return rc;
> }
>
Hi Naoya,
I believe we need to set 'rc = 0' in the !folio_test_hugetlb(). I put
together the following patch based on mm-stable. Please take a look.
>From f19fbfab324d7d17de4a1e814f95ee655950c58e Mon Sep 17 00:00:00 2001
From: Mike Kravetz <mike.kravetz@xxxxxxxxxx>
Date: Mon, 16 Oct 2023 19:55:49 -0700
Subject: [PATCH] hugetlb: check for hugetlb folio before vmemmap_restore
In commit d8f5f7e445f0 ("hugetlb: set hugetlb page flag before
optimizing vmemmap") checks were added to print a warning if
hugetlb_vmemmap_restore was called on a non-hugetlb page. This
was mostly due to ordering issues in the hugetlb page set up and
tear down sequencees. One place missed was the routine
dissolve_free_huge_page. Naoya Horiguchi noted: "I saw that
VM_WARN_ON_ONCE() in hugetlb_vmemmap_restore is triggered when
memory_failure() is called on a free hugetlb page with vmemmap
optimization disabled (the warning is not triggered if vmemmap
optimization is enabled). I think that we need check
folio_test_hugetlb() before dissolve_free_huge_page() calls
hugetlb_vmemmap_restore_folio()."
Perform the check as suggested by Naoya.
Fixes: d8f5f7e445f0 ("hugetlb: set hugetlb page flag before optimizing vmemmap")
Suggested-by: Naoya Horiguchi <naoya.horiguchi@xxxxxxxxx>
Signed-off-by: Mike Kravetz <mike.kravetz@xxxxxxxxxx>
---
mm/hugetlb.c | 24 +++++++++++++++---------
1 file changed, 15 insertions(+), 9 deletions(-)
diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 36b40bc9ac25..13736cbb2c19 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -2290,17 +2290,23 @@ int dissolve_free_huge_page(struct page *page)
* need to adjust max_huge_pages if the page is not freed.
* Attempt to allocate vmemmmap here so that we can take
* appropriate action on failure.
+ *
+ * The folio_test_hugetlb check here is because
+ * remove_hugetlb_folio will clear hugetlb folio flag for
+ * non-vmemmap optimized hugetlb folios.
*/
- rc = hugetlb_vmemmap_restore(h, &folio->page);
- if (!rc) {
- update_and_free_hugetlb_folio(h, folio, false);
- } else {
- spin_lock_irq(&hugetlb_lock);
- add_hugetlb_folio(h, folio, false);
- h->max_huge_pages++;
- spin_unlock_irq(&hugetlb_lock);
- }
+ if (folio_test_hugetlb(folio)) {
+ rc = hugetlb_vmemmap_restore(h, &folio->page);
+ if (rc) {
+ spin_lock_irq(&hugetlb_lock);
+ add_hugetlb_folio(h, folio, false);
+ h->max_huge_pages++;
+ goto out;
+ }
+ } else
+ rc = 0;
+ update_and_free_hugetlb_folio(h, folio, false);
return rc;
}
out:
--
2.41.0
