From e9fe92ae0cd28aac5cf6d3fb8442825c22fbd3a6 Mon Sep 17 00:00:00 2001 From: Mina Almasry Date: Wed, 1 Apr 2020 21:11:21 -0700 Subject: hugetlb_cgroup: add reservation accounting for private mappings Normally the pointer to the cgroup to uncharge hangs off the struct page, and gets queried when it's time to free the page. With hugetlb_cgroup reservations, this is not possible. Because it's possible for a page to be reserved by one task and actually faulted in by another task. The best place to put the hugetlb_cgroup pointer to uncharge for reservations is in the resv_map. But, because the resv_map has different semantics for private and shared mappings, the code patch to charge/uncharge shared and private mappings is different. This patch implements charging and uncharging for private mappings. For private mappings, the counter to uncharge is in resv_map->reservation_counter. On initializing the resv_map this is set to NULL. On reservation of a region in private mapping, the tasks hugetlb_cgroup is charged and the hugetlb_cgroup is placed is resv_map->reservation_counter. On hugetlb_vm_op_close, we uncharge resv_map->reservation_counter. [akpm@linux-foundation.org: forward declare struct resv_map] Signed-off-by: Mina Almasry Signed-off-by: Andrew Morton Reviewed-by: Mike Kravetz Acked-by: David Rientjes Cc: Greg Thelen Cc: Sandipan Das Cc: Shakeel Butt Cc: Shuah Khan Link: http://lkml.kernel.org/r/20200211213128.73302-3-almasrymina@google.com Signed-off-by: Linus Torvalds --- mm/hugetlb.c | 47 ++++++++++++++++++++++++++++++++++++++++++++--- 1 file changed, 44 insertions(+), 3 deletions(-) (limited to 'mm/hugetlb.c') diff --git a/mm/hugetlb.c b/mm/hugetlb.c index ffc52d985751..5b6d83ee0a02 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -650,6 +650,25 @@ static void set_vma_private_data(struct vm_area_struct *vma, vma->vm_private_data = (void *)value; } +static void +resv_map_set_hugetlb_cgroup_uncharge_info(struct resv_map *resv_map, + struct hugetlb_cgroup *h_cg, + struct hstate *h) +{ +#ifdef CONFIG_CGROUP_HUGETLB + if (!h_cg || !h) { + resv_map->reservation_counter = NULL; + resv_map->pages_per_hpage = 0; + resv_map->css = NULL; + } else { + resv_map->reservation_counter = + &h_cg->rsvd_hugepage[hstate_index(h)]; + resv_map->pages_per_hpage = pages_per_huge_page(h); + resv_map->css = &h_cg->css; + } +#endif +} + struct resv_map *resv_map_alloc(void) { struct resv_map *resv_map = kmalloc(sizeof(*resv_map), GFP_KERNEL); @@ -666,6 +685,13 @@ struct resv_map *resv_map_alloc(void) INIT_LIST_HEAD(&resv_map->regions); resv_map->adds_in_progress = 0; + /* + * Initialize these to 0. On shared mappings, 0's here indicate these + * fields don't do cgroup accounting. On private mappings, these will be + * re-initialized to the proper values, to indicate that hugetlb cgroup + * reservations are to be un-charged from here. + */ + resv_map_set_hugetlb_cgroup_uncharge_info(resv_map, NULL, NULL); INIT_LIST_HEAD(&resv_map->region_cache); list_add(&rg->link, &resv_map->region_cache); @@ -3296,9 +3322,7 @@ static void hugetlb_vm_op_close(struct vm_area_struct *vma) end = vma_hugecache_offset(h, vma, vma->vm_end); reserve = (end - start) - region_count(resv, start, end); - - kref_put(&resv->refs, resv_map_release); - + hugetlb_cgroup_uncharge_counter(resv, start, end); if (reserve) { /* * Decrement reserve counts. The global reserve count may be @@ -3307,6 +3331,8 @@ static void hugetlb_vm_op_close(struct vm_area_struct *vma) gbl_reserve = hugepage_subpool_put_pages(spool, reserve); hugetlb_acct_memory(h, -gbl_reserve); } + + kref_put(&resv->refs, resv_map_release); } static int hugetlb_vm_op_split(struct vm_area_struct *vma, unsigned long addr) @@ -4691,6 +4717,7 @@ int hugetlb_reserve_pages(struct inode *inode, struct hstate *h = hstate_inode(inode); struct hugepage_subpool *spool = subpool_inode(inode); struct resv_map *resv_map; + struct hugetlb_cgroup *h_cg; long gbl_reserve; /* This should never happen */ @@ -4724,12 +4751,26 @@ int hugetlb_reserve_pages(struct inode *inode, chg = region_chg(resv_map, from, to); } else { + /* Private mapping. */ resv_map = resv_map_alloc(); if (!resv_map) return -ENOMEM; chg = to - from; + if (hugetlb_cgroup_charge_cgroup_rsvd( + hstate_index(h), chg * pages_per_huge_page(h), + &h_cg)) { + kref_put(&resv_map->refs, resv_map_release); + return -ENOMEM; + } + + /* + * Since this branch handles private mappings, we attach the + * counter to uncharge for this reservation off resv_map. + */ + resv_map_set_hugetlb_cgroup_uncharge_info(resv_map, h_cg, h); + set_vma_resv_map(vma, resv_map); set_vma_resv_flags(vma, HPAGE_RESV_OWNER); } -- cgit v1.2.3