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mm: hugetlb: move mem_cgroup_charge_hugetlb() earlier in allocation

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Move mem_cgroup_charge_hugetlb() earlier in the folio allocation process. 
This change draws a cleaner line between memcg charging and the subsequent
hugetlb-specific reservation logic for VMAs and subpools.

While it would be ideal to make all accounting and reservations perfectly
symmetric, mem_cgroup_charge_hugetlb() is a complex operation that cannot
be performed under the hugetlb_lock.  Moving the charge to this earlier
point ensures that memcg charging is handled before the code begins
manipulating subpool and VMA-specific state.  These two types of
accounting will be separated in a future patch.

If mem_cgroup_charge_hugetlb() fails, the code now branches to
out_subpool_put to ensure the folio is freed and the subpool references
are handled correctly.

Link: https://lore.kernel.org/20260702-hugetlb-open-up-v4-5-d53cefcccf34@google.com
Signed-off-by: Ackerley Tng <ackerleytng@google.com>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Byungchul Park <byungchul@sk.com>
Cc: David Hildenbrand <david@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: "Edgecombe, Rick P" <rick.p.edgecombe@intel.com>
Cc: Frank van der Linden <fvdl@google.com>
Cc: Gregory Price <gourry@gourry.net>
Cc: "Huang, Ying" <ying.huang@linux.alibaba.com>
Cc: James Houghton <jthoughton@google.com>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Jiaqi Yan <jiaqiyan@google.com>
Cc: Joshua Hahn <joshua.hahnjy@gmail.com>
Cc: Matthew Brost <matthew.brost@intel.com>
Cc: Michael Roth <michael.roth@amd.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Pasha Tatashin <pasha.tatashin@soleen.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Pratyush Yadav <pratyush@kernel.org>
Cc: Qi Zheng <qi.zheng@linux.dev>
Cc: Rakie Kim <rakie.kim@sk.com>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Sean Christopherson <seanjc@google.com>
Cc: Shakeel Butt <shakeel.butt@linux.dev>
Cc: Shivank Garg <shivankg@amd.com>
Cc: Vishal Annapurve <vannapurve@google.com>
Cc: Yan Zhao <yan.y.zhao@intel.com>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Ackerley Tng 2026-07-02 09:21:49 -07:00 committed by Andrew Morton
parent 564b2eeeb9
commit 177e1cbbb5
1 changed files with 18 additions and 13 deletions
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31
mm/hugetlb.c
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@ -2977,6 +2977,24 @@ struct folio *alloc_hugetlb_folio(struct vm_area_struct *vma,
spin_unlock_irq(&hugetlb_lock);
ret = mem_cgroup_charge_hugetlb(folio, gfp | __GFP_RETRY_MAYFAIL);
/*
* Unconditionally increment NR_HUGETLB here. If it turns out that
* mem_cgroup_charge_hugetlb failed, then immediately free the page and
* decrement NR_HUGETLB.
*/
lruvec_stat_mod_folio(folio, NR_HUGETLB, pages_per_huge_page(h));
if (ret == -ENOMEM) {
free_huge_folio(folio);
/*
* Skip uncharging hugetlb_cgroup since the charges
* were committed to the folio and freeing the folio
* would have cleared those up.
*/
goto out_subpool_put;
}
hugetlb_set_folio_subpool(folio, spool);
if (map_chg != MAP_CHG_ENFORCED) {
@ -3004,19 +3022,6 @@ struct folio *alloc_hugetlb_folio(struct vm_area_struct *vma,
}
}
ret = mem_cgroup_charge_hugetlb(folio, gfp | __GFP_RETRY_MAYFAIL);
/*
* Unconditionally increment NR_HUGETLB here. If it turns out that
* mem_cgroup_charge_hugetlb failed, then immediately free the page and
* decrement NR_HUGETLB.
*/
lruvec_stat_mod_folio(folio, NR_HUGETLB, pages_per_huge_page(h));
if (ret == -ENOMEM) {
free_huge_folio(folio);
return ERR_PTR(-ENOMEM);
}
return folio;
out_uncharge_cgroup: