From: Ackerley Tng 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. Signed-off-by: Ackerley Tng --- mm/hugetlb.c | 31 ++++++++++++++++++------------- 1 file changed, 18 insertions(+), 13 deletions(-) diff --git a/mm/hugetlb.c b/mm/hugetlb.c index 68c21305fc86a..4159b3565a9be 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -2975,6 +2975,24 @@ 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) { @@ -3002,19 +3020,6 @@ 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: -- 2.54.0.545.g6539524ca2-goog