For shared mappings, the pointer to the hugetlb_cgroup to uncharge lives in the resv_map entries, in file_region->reservation_counter.
After a call to region_chg, we charge the approprate hugetlb_cgroup, and if successful, we pass on the hugetlb_cgroup info to a follow up region_add call. When a file_region entry is added to the resv_map via region_add, we put the pointer to that cgroup in file_region->reservation_counter. If charging doesn't succeed, we report the error to the caller, so that the kernel fails the reservation.
On region_del, which is when the hugetlb memory is unreserved, we also uncharge the file_region->reservation_counter.
Signed-off-by: Mina Almasry almasrymina@google.com
---
Changes in v10: - Deleted duplicated code snippet. Changes in V9: - Updated for hugetlb reservation repareting.
--- mm/hugetlb.c | 156 ++++++++++++++++++++++++++++++++++++++++----------- 1 file changed, 124 insertions(+), 32 deletions(-)
diff --git a/mm/hugetlb.c b/mm/hugetlb.c index de0028e9a8630..9bcfc12c5d214 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -243,6 +243,16 @@ struct file_region { struct list_head link; long from; long to; +#ifdef CONFIG_CGROUP_HUGETLB + /* + * On shared mappings, each reserved region appears as a struct + * file_region in resv_map. These fields hold the info needed to + * uncharge each reservation. + */ + struct page_counter *reservation_counter; + unsigned long pages_per_hpage; + struct cgroup_subsys_state *css; +#endif };
/* Helper that removes a struct file_region from the resv_map cache and returns @@ -266,6 +276,25 @@ get_file_region_entry_from_cache(struct resv_map *resv, long from, long to) return nrg; }
+/* Helper that records hugetlb_cgroup uncharge info. */ +static void record_hugetlb_cgroup_uncharge_info(struct hugetlb_cgroup *h_cg, + struct file_region *nrg, + struct hstate *h) +{ +#ifdef CONFIG_CGROUP_HUGETLB + if (h_cg) { + nrg->reservation_counter = + &h_cg->reserved_hugepage[hstate_index(h)]; + nrg->pages_per_hpage = pages_per_huge_page(h); + nrg->css = &h_cg->css; + } else { + nrg->reservation_counter = NULL; + nrg->pages_per_hpage = 0; + nrg->css = NULL; + } +#endif +} + /* Must be called with resv->lock held. Calling this with count_only == true * will count the number of pages to be added but will not modify the linked * list. If regions_needed != NULL and count_only == true, then regions_needed @@ -273,7 +302,9 @@ get_file_region_entry_from_cache(struct resv_map *resv, long from, long to) * add the regions for this range. */ static long add_reservation_in_range(struct resv_map *resv, long f, long t, - long *regions_needed, bool count_only) + struct hugetlb_cgroup *h_cg, + struct hstate *h, long *regions_needed, + bool count_only) { long add = 0; struct list_head *head = &resv->regions; @@ -312,6 +343,8 @@ static long add_reservation_in_range(struct resv_map *resv, long f, long t, if (!count_only) { nrg = get_file_region_entry_from_cache( resv, last_accounted_offset, rg->from); + record_hugetlb_cgroup_uncharge_info(h_cg, nrg, + h); list_add(&nrg->link, rg->link.prev); } else if (regions_needed) *regions_needed += 1; @@ -328,11 +361,13 @@ static long add_reservation_in_range(struct resv_map *resv, long f, long t, if (!count_only) { nrg = get_file_region_entry_from_cache( resv, last_accounted_offset, t); + record_hugetlb_cgroup_uncharge_info(h_cg, nrg, h); list_add(&nrg->link, rg->link.prev); } else if (regions_needed) *regions_needed += 1; }
+ VM_BUG_ON(add < 0); return add; }
@@ -353,7 +388,8 @@ static long add_reservation_in_range(struct resv_map *resv, long f, long t, * fail; region_chg will always allocate at least 1 entry and a region_add for * 1 page will only require at most 1 entry. */ -static long region_add(struct resv_map *resv, long f, long t, +static long region_add(struct hstate *h, struct hugetlb_cgroup *h_cg, + struct resv_map *resv, long f, long t, long in_regions_needed) { long add = 0, actual_regions_needed = 0, i = 0; @@ -366,7 +402,8 @@ static long region_add(struct resv_map *resv, long f, long t, retry:
/* Count how many regions are actually needed to execute this add. */ - add_reservation_in_range(resv, f, t, &actual_regions_needed, true); + add_reservation_in_range(resv, f, t, NULL, NULL, &actual_regions_needed, + true);
/* * Check for sufficient descriptors in the cache to accommodate @@ -404,7 +441,7 @@ static long region_add(struct resv_map *resv, long f, long t, goto retry; }
- add = add_reservation_in_range(resv, f, t, NULL, false); + add = add_reservation_in_range(resv, f, t, h_cg, h, NULL, false);
resv->adds_in_progress -= in_regions_needed;
@@ -452,7 +489,8 @@ static long region_chg(struct resv_map *resv, long f, long t, spin_lock(&resv->lock);
/* Count how many hugepages in this range are NOT respresented. */ - chg = add_reservation_in_range(resv, f, t, out_regions_needed, true); + chg = add_reservation_in_range(resv, f, t, NULL, NULL, + out_regions_needed, true);
if (*out_regions_needed == 0) *out_regions_needed = 1; @@ -524,6 +562,29 @@ static void region_abort(struct resv_map *resv, long f, long t, spin_unlock(&resv->lock); }
+static void uncharge_cgroup_if_shared_mapping(struct resv_map *resv, + struct file_region *rg, + unsigned long nr_pages) +{ +#ifdef CONFIG_CGROUP_HUGETLB + /* + * If resv->reservation_counter is NULL, then this is either a shared + * reservation, or cgroup charging is disabled on this resv_map. + * + * If the cgroup charging is disabled, then rg->reservation_counter is + * NULL and the uncharge counter call is a no-op. If the mapping is + * shared then the reserved memory is tracked in the file_struct + * entries inside of resv_map. So we need to uncharge the memory here. + */ + if (rg->reservation_counter && rg->pages_per_hpage && nr_pages > 0 && + !resv->reservation_counter) { + hugetlb_cgroup_uncharge_counter(rg->reservation_counter, + nr_pages * rg->pages_per_hpage, + rg->css); + } +#endif +} + /* * Delete the specified range [f, t) from the reserve map. If the * t parameter is LONG_MAX, this indicates that ALL regions after f @@ -588,11 +649,22 @@ static long region_del(struct resv_map *resv, long f, long t) /* New entry for end of split region */ nrg->from = t; nrg->to = rg->to; + +#ifdef CONFIG_CGROUP_HUGETLB + nrg->reservation_counter = rg->reservation_counter; + nrg->pages_per_hpage = rg->pages_per_hpage; + nrg->css = rg->css; + css_get(rg->css); +#endif + INIT_LIST_HEAD(&nrg->link);
/* Original entry is trimmed */ rg->to = f;
+ uncharge_cgroup_if_shared_mapping(resv, rg, + nrg->to - nrg->from); + list_add(&nrg->link, &rg->link); nrg = NULL; break; @@ -600,6 +672,8 @@ static long region_del(struct resv_map *resv, long f, long t)
if (f <= rg->from && t >= rg->to) { /* Remove entire region */ del += rg->to - rg->from; + uncharge_cgroup_if_shared_mapping(resv, rg, + rg->to - rg->from); list_del(&rg->link); kfree(rg); continue; @@ -608,14 +682,20 @@ static long region_del(struct resv_map *resv, long f, long t) if (f <= rg->from) { /* Trim beginning of region */ del += t - rg->from; rg->from = t; + + uncharge_cgroup_if_shared_mapping(resv, rg, + t - rg->from); } else { /* Trim end of region */ del += rg->to - f; rg->to = f; + + uncharge_cgroup_if_shared_mapping(resv, rg, rg->to - f); } }
spin_unlock(&resv->lock); kfree(nrg); + return del; }
@@ -2002,7 +2082,7 @@ static long __vma_reservation_common(struct hstate *h, VM_BUG_ON(dummy_out_regions_needed != 1); break; case VMA_COMMIT_RESV: - ret = region_add(resv, idx, idx + 1, 1); + ret = region_add(NULL, NULL, resv, idx, idx + 1, 1); /* region_add calls of range 1 should never fail. */ VM_BUG_ON(ret < 0); break; @@ -2012,7 +2092,7 @@ static long __vma_reservation_common(struct hstate *h, break; case VMA_ADD_RESV: if (vma->vm_flags & VM_MAYSHARE) { - ret = region_add(resv, idx, idx + 1, 1); + ret = region_add(NULL, NULL, resv, idx, idx + 1, 1); /* region_add calls of range 1 should never fail. */ VM_BUG_ON(ret < 0); } else { @@ -4679,7 +4759,7 @@ 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; + struct hugetlb_cgroup *h_cg = NULL; long gbl_reserve, regions_needed = 0;
/* This should never happen */ @@ -4720,23 +4800,6 @@ int hugetlb_reserve_pages(struct inode *inode,
chg = to - from;
- if (hugetlb_cgroup_charge_cgroup(hstate_index(h), - chg * pages_per_huge_page(h), - &h_cg, true)) { - kref_put(&resv_map->refs, resv_map_release); - return -ENOMEM; - } - -#ifdef CONFIG_CGROUP_HUGETLB - /* - * Since this branch handles private mappings, we attach the - * counter to uncharge for this reservation off resv_map. - */ - resv_map->reservation_counter = - &h_cg->reserved_hugepage[hstate_index(h)]; - resv_map->pages_per_hpage = pages_per_huge_page(h); -#endif - set_vma_resv_map(vma, resv_map); set_vma_resv_flags(vma, HPAGE_RESV_OWNER); } @@ -4746,6 +4809,26 @@ int hugetlb_reserve_pages(struct inode *inode, goto out_err; }
+ ret = hugetlb_cgroup_charge_cgroup( + hstate_index(h), chg * pages_per_huge_page(h), &h_cg, true); + + if (ret < 0) { + ret = -ENOMEM; + goto out_err; + } + +#ifdef CONFIG_CGROUP_HUGETLB + if (vma && !(vma->vm_flags & VM_MAYSHARE) && h_cg) { + /* For private mappings, the hugetlb_cgroup uncharge info hangs + * of the resv_map. + */ + resv_map->reservation_counter = + &h_cg->reserved_hugepage[hstate_index(h)]; + resv_map->pages_per_hpage = pages_per_huge_page(h); + resv_map->css = &h_cg->css; + } +#endif + /* * There must be enough pages in the subpool for the mapping. If * the subpool has a minimum size, there may be some global @@ -4754,7 +4837,7 @@ int hugetlb_reserve_pages(struct inode *inode, gbl_reserve = hugepage_subpool_get_pages(spool, chg); if (gbl_reserve < 0) { ret = -ENOSPC; - goto out_err; + goto out_uncharge_cgroup; }
/* @@ -4763,9 +4846,7 @@ int hugetlb_reserve_pages(struct inode *inode, */ ret = hugetlb_acct_memory(h, gbl_reserve); if (ret < 0) { - /* put back original number of pages, chg */ - (void)hugepage_subpool_put_pages(spool, chg); - goto out_err; + goto out_put_pages; }
/* @@ -4780,7 +4861,7 @@ int hugetlb_reserve_pages(struct inode *inode, * else has to be done for private mappings here */ if (!vma || vma->vm_flags & VM_MAYSHARE) { - add = region_add(resv_map, from, to, regions_needed); + add = region_add(h, h_cg, resv_map, from, to, regions_needed);
if (unlikely(add < 0)) { hugetlb_acct_memory(h, -gbl_reserve); @@ -4797,12 +4878,23 @@ int hugetlb_reserve_pages(struct inode *inode, */ long rsv_adjust;
- rsv_adjust = hugepage_subpool_put_pages(spool, - chg - add); + hugetlb_cgroup_uncharge_cgroup( + hstate_index(h), + (chg - add) * pages_per_huge_page(h), h_cg, + true); + + rsv_adjust = + hugepage_subpool_put_pages(spool, chg - add); hugetlb_acct_memory(h, -rsv_adjust); } } return 0; +out_put_pages: + /* put back original number of pages, chg */ + (void)hugepage_subpool_put_pages(spool, chg); +out_uncharge_cgroup: + hugetlb_cgroup_uncharge_cgroup( + hstate_index(h), chg * pages_per_huge_page(h), h_cg, true); out_err: if (!vma || vma->vm_flags & VM_MAYSHARE) /* Only call region_abort if the region_chg succeeded but the -- 2.25.0.rc1.283.g88dfdc4193-goog