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authorSteve Sistare <steven.sistare@oracle.com>2024-09-03 16:25:19 +0200
committerAndrew Morton <akpm@linux-foundation.org>2024-09-26 23:01:43 +0200
commit26a8ea80929c518bdec5e53a5776f95919b7c88e (patch)
tree735807d1340f0297a99e5ea65c58f867be55e3e9
parentmm/hugetlb: fix memfd_pin_folios free_huge_pages leak (diff)
downloadlinux-26a8ea80929c518bdec5e53a5776f95919b7c88e.tar.xz
linux-26a8ea80929c518bdec5e53a5776f95919b7c88e.zip
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.h10
-rw-r--r--mm/hugetlb.c17
-rw-r--r--mm/memfd.c9
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,