diff options
| author | Steve Sistare <steven.sistare@oracle.com> | 2024-09-03 07:25:19 -0700 |
|---|---|---|
| committer | Andrew Morton <akpm@linux-foundation.org> | 2024-09-26 14:01:43 -0700 |
| commit | 26a8ea80929c518bdec5e53a5776f95919b7c88e (patch) | |
| tree | 735807d1340f0297a99e5ea65c58f867be55e3e9 | |
| parent | c56b6f3d801d7ec8965993342bdd9e2972b6cb8e (diff) | |
mm/hugetlb: fix memfd_pin_folios resv_huge_pages leak
memfd_pin_folios followed by unpin_folios leaves resv_huge_pages elevated
if the pages were not already faulted in. During a normal page fault,
resv_huge_pages is consumed here:
hugetlb_fault()
alloc_hugetlb_folio()
dequeue_hugetlb_folio_vma()
dequeue_hugetlb_folio_nodemask()
dequeue_hugetlb_folio_node_exact()
free_huge_pages--
resv_huge_pages--
During memfd_pin_folios, the page is created by calling
alloc_hugetlb_folio_nodemask instead of alloc_hugetlb_folio, and
resv_huge_pages is not modified:
memfd_alloc_folio()
alloc_hugetlb_folio_nodemask()
dequeue_hugetlb_folio_nodemask()
dequeue_hugetlb_folio_node_exact()
free_huge_pages--
alloc_hugetlb_folio_nodemask has other callers that must not modify
resv_huge_pages. Therefore, to fix, define an alternate version of
alloc_hugetlb_folio_nodemask for this call site that adjusts
resv_huge_pages.
Link: https://lkml.kernel.org/r/1725373521-451395-4-git-send-email-steven.sistare@oracle.com
Fixes: 89c1905d9c14 ("mm/gup: introduce memfd_pin_folios() for pinning memfd folios")
Signed-off-by: Steve Sistare <steven.sistare@oracle.com>
Acked-by: Vivek Kasireddy <vivek.kasireddy@intel.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Jason Gunthorpe <jgg@nvidia.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Peter Xu <peterx@redhat.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
| -rw-r--r-- | include/linux/hugetlb.h | 10 | ||||
| -rw-r--r-- | mm/hugetlb.c | 17 | ||||
| -rw-r--r-- | mm/memfd.c | 9 |
3 files changed, 31 insertions, 5 deletions
diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h index 98c47c394b89..e4697539b665 100644 --- a/include/linux/hugetlb.h +++ b/include/linux/hugetlb.h @@ -692,6 +692,9 @@ struct folio *alloc_hugetlb_folio(struct vm_area_struct *vma, struct folio *alloc_hugetlb_folio_nodemask(struct hstate *h, int preferred_nid, nodemask_t *nmask, gfp_t gfp_mask, bool allow_alloc_fallback); +struct folio *alloc_hugetlb_folio_reserve(struct hstate *h, int preferred_nid, + nodemask_t *nmask, gfp_t gfp_mask); + int hugetlb_add_to_page_cache(struct folio *folio, struct address_space *mapping, pgoff_t idx); void restore_reserve_on_error(struct hstate *h, struct vm_area_struct *vma, @@ -1060,6 +1063,13 @@ static inline struct folio *alloc_hugetlb_folio(struct vm_area_struct *vma, } static inline struct folio * +alloc_hugetlb_folio_reserve(struct hstate *h, int preferred_nid, + nodemask_t *nmask, gfp_t gfp_mask) +{ + return NULL; +} + +static inline struct folio * alloc_hugetlb_folio_nodemask(struct hstate *h, int preferred_nid, nodemask_t *nmask, gfp_t gfp_mask, bool allow_alloc_fallback) diff --git a/mm/hugetlb.c b/mm/hugetlb.c index def84d8bcf2d..190fa05635f4 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -2390,6 +2390,23 @@ struct folio *alloc_buddy_hugetlb_folio_with_mpol(struct hstate *h, return folio; } +struct folio *alloc_hugetlb_folio_reserve(struct hstate *h, int preferred_nid, + nodemask_t *nmask, gfp_t gfp_mask) +{ + struct folio *folio; + + spin_lock_irq(&hugetlb_lock); + folio = dequeue_hugetlb_folio_nodemask(h, gfp_mask, preferred_nid, + nmask); + if (folio) { + VM_BUG_ON(!h->resv_huge_pages); + h->resv_huge_pages--; + } + + spin_unlock_irq(&hugetlb_lock); + return folio; +} + /* folio migration callback function */ struct folio *alloc_hugetlb_folio_nodemask(struct hstate *h, int preferred_nid, nodemask_t *nmask, gfp_t gfp_mask, bool allow_alloc_fallback) diff --git a/mm/memfd.c b/mm/memfd.c index e7b7c5294d59..bfe0e7189a37 100644 --- a/mm/memfd.c +++ b/mm/memfd.c @@ -82,11 +82,10 @@ struct folio *memfd_alloc_folio(struct file *memfd, pgoff_t idx) gfp_mask = htlb_alloc_mask(hstate_file(memfd)); gfp_mask &= ~(__GFP_HIGHMEM | __GFP_MOVABLE); - folio = alloc_hugetlb_folio_nodemask(hstate_file(memfd), - numa_node_id(), - NULL, - gfp_mask, - false); + folio = alloc_hugetlb_folio_reserve(hstate_file(memfd), + numa_node_id(), + NULL, + gfp_mask); if (folio && folio_try_get(folio)) { err = hugetlb_add_to_page_cache(folio, memfd->f_mapping, |