HugeTLB folios are currently charged to the memcg of the allocating task. This gives the wrong result when a userfaultfd handler populates a HugeTLB VMA that belongs to another process. The UFFDIO_COPY ioctl operates on the userfaultfd context's mm, but get_mem_cgroup_from_current() charges the folio to the handler's memcg instead. This can be reproduced by placing the faulting process and its userfaultfd handler in different memory cgroups. Have the target process register a HugeTLB mapping with userfaultfd, trigger a missing fault, and let the handler resolve it with UFFDIO_COPY. The hugepage usage is then reported in the handler's memory.current instead of the target's. The generic userfaultfd population path avoids this problem by charging folios to dst_vma->vm_mm. Pass the target mm through hugetlb_alloc_folio() and charge the folio by using get_mem_cgroup_from_mm(). This preserves the existing charge timing and error handling while making HugeTLB userfaultfd population consistent with the generic path. Fixes: 8cba9576df60 ("hugetlb: memcg: account hugetlb-backed memory in memory controller") Cc: stable@vger.kernel.org Signed-off-by: Jinmeng Zhou --- include/linux/hugetlb.h | 3 ++- include/linux/memcontrol.h | 8 +++++--- mm/hugetlb.c | 9 ++++++--- mm/memcontrol.c | 6 ++++-- 4 files changed, 17 insertions(+), 9 deletions(-) diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h index 16c4c4caa126..45ada75dc04e 100644 --- a/include/linux/hugetlb.h +++ b/include/linux/hugetlb.h @@ -699,7 +699,8 @@ enum hugetlb_alloc_flag { #define HUGETLB_ALLOC_USE_GLOBAL_RESERVATIONS BIT(HUGETLB_ALLOC_USE_GLOBAL_RESERVATIONS_BIT) struct folio *hugetlb_alloc_folio(struct hstate *h, - struct mempolicy_interpreted *mpoli, u8 alloc_flags); + struct mempolicy_interpreted *mpoli, struct mm_struct *mm, + u8 alloc_flags); struct folio *alloc_hugetlb_folio(struct vm_area_struct *vma, unsigned long addr, bool cow_from_owner); struct folio *alloc_hugetlb_folio_nodemask(struct hstate *h, int preferred_nid, diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h index 7d1c0ce189a8..362af58e50a4 100644 --- a/include/linux/memcontrol.h +++ b/include/linux/memcontrol.h @@ -662,7 +662,8 @@ static inline int mem_cgroup_charge(struct folio *folio, struct mm_struct *mm, return __mem_cgroup_charge(folio, mm, gfp); } -int mem_cgroup_charge_hugetlb(struct folio* folio, gfp_t gfp); +int mem_cgroup_charge_hugetlb(struct folio *folio, struct mm_struct *mm, + gfp_t gfp); int mem_cgroup_swapin_charge_folio(struct folio *folio, unsigned short id, struct mm_struct *mm, gfp_t gfp); @@ -1156,9 +1157,10 @@ static inline int mem_cgroup_charge(struct folio *folio, return 0; } -static inline int mem_cgroup_charge_hugetlb(struct folio* folio, gfp_t gfp) +static inline int mem_cgroup_charge_hugetlb(struct folio *folio, + struct mm_struct *mm, gfp_t gfp) { - return 0; + return 0; } static inline int mem_cgroup_swapin_charge_folio(struct folio *folio, diff --git a/mm/hugetlb.c b/mm/hugetlb.c index 785772845795..5ab5a5141574 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -2816,6 +2816,7 @@ void wait_for_freed_hugetlb_folios(void) * hugetlb_alloc_folio - Allocate a hugetlb folio. * @h: Hugetlb state control block. * @mpoli: Interpreted memory policy to use for allocation. + * @mm: Memory descriptor of the allocation target. * @alloc_flags: Flags controlling the allocation behavior. * * Allocates a hugetlb folio and handles cgroup charging and global hstate @@ -2826,7 +2827,8 @@ void wait_for_freed_hugetlb_folios(void) * -ENOMEM if mem cgroup charging fails. */ struct folio *hugetlb_alloc_folio(struct hstate *h, - struct mempolicy_interpreted *mpoli, u8 alloc_flags) + struct mempolicy_interpreted *mpoli, struct mm_struct *mm, + u8 alloc_flags) { bool charge_hugetlb_cgroup_rsvd = alloc_flags & HUGETLB_ALLOC_CHARG_CGROUP_RSVD; @@ -2881,7 +2883,8 @@ struct folio *hugetlb_alloc_folio(struct hstate *h, spin_unlock_irq(&hugetlb_lock); - ret = mem_cgroup_charge_hugetlb(folio, gfp | __GFP_RETRY_MAYFAIL); + ret = mem_cgroup_charge_hugetlb(folio, mm, + gfp | __GFP_RETRY_MAYFAIL); /* * Unconditionally increment NR_HUGETLB here because if * mem_cgroup_charge_hugetlb failed, freeing the page will @@ -3020,7 +3023,7 @@ struct folio *alloc_hugetlb_folio(struct vm_area_struct *vma, .nodemask = nodemask, }; - folio = hugetlb_alloc_folio(h, &mpoli, alloc_flags); + folio = hugetlb_alloc_folio(h, &mpoli, vma->vm_mm, alloc_flags); mpol_cond_put(mpol); diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 1271d390b617..0b795bf1e6cf 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -5233,6 +5233,7 @@ int __mem_cgroup_charge(struct folio *folio, struct mm_struct *mm, gfp_t gfp) /** * mem_cgroup_charge_hugetlb - charge the memcg for a hugetlb folio * @folio: folio being charged + * @mm: mm context of the allocation target * @gfp: reclaim mode * * This function is called when allocating a huge page folio, after the page has @@ -5242,9 +5243,10 @@ int __mem_cgroup_charge(struct folio *folio, struct mm_struct *mm, gfp_t gfp) * Returns ENOMEM if the memcg is already full. * Returns 0 if either the charge was successful, or if we skip the charging. */ -int mem_cgroup_charge_hugetlb(struct folio *folio, gfp_t gfp) +int mem_cgroup_charge_hugetlb(struct folio *folio, struct mm_struct *mm, + gfp_t gfp) { - struct mem_cgroup *memcg = get_mem_cgroup_from_current(); + struct mem_cgroup *memcg = get_mem_cgroup_from_mm(mm); int ret = 0; /* -- 2.39.5