From e0dcd8a05be438b3d2e49ef61441ea3a463663f8 Mon Sep 17 00:00:00 2001 From: Hugh Dickins Date: Sun, 5 Jun 2011 22:03:13 -0700 Subject: mm: fix ENOSPC returned by handle_mm_fault() Al Viro observes that in the hugetlb case, handle_mm_fault() may return a value of the kind ENOSPC when its caller is expecting a value of the kind VM_FAULT_SIGBUS: fix alloc_huge_page()'s failure returns. Signed-off-by: Hugh Dickins Acked-by: Al Viro Cc: stable@kernel.org Signed-off-by: Linus Torvalds --- mm/hugetlb.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'mm/hugetlb.c') diff --git a/mm/hugetlb.c b/mm/hugetlb.c index f33bb319b73f..6402458fee38 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -1033,10 +1033,10 @@ static struct page *alloc_huge_page(struct vm_area_struct *vma, */ chg = vma_needs_reservation(h, vma, addr); if (chg < 0) - return ERR_PTR(chg); + return ERR_PTR(-VM_FAULT_OOM); if (chg) if (hugetlb_get_quota(inode->i_mapping, chg)) - return ERR_PTR(-ENOSPC); + return ERR_PTR(-VM_FAULT_SIGBUS); spin_lock(&hugetlb_lock); page = dequeue_huge_page_vma(h, vma, addr, avoid_reserve); -- cgit v1.2.3 From b0320c7b7d1ac1bd5c2d9dff3258524ab39bad32 Mon Sep 17 00:00:00 2001 From: Rafael Aquini Date: Wed, 15 Jun 2011 15:08:39 -0700 Subject: mm: fix negative commitlimit when gigantic hugepages are allocated When 1GB hugepages are allocated on a system, free(1) reports less available memory than what really is installed in the box. Also, if the total size of hugepages allocated on a system is over half of the total memory size, CommitLimit becomes a negative number. The problem is that gigantic hugepages (order > MAX_ORDER) can only be allocated at boot with bootmem, thus its frames are not accounted to 'totalram_pages'. However, they are accounted to hugetlb_total_pages() What happens to turn CommitLimit into a negative number is this calculation, in fs/proc/meminfo.c: allowed = ((totalram_pages - hugetlb_total_pages()) * sysctl_overcommit_ratio / 100) + total_swap_pages; A similar calculation occurs in __vm_enough_memory() in mm/mmap.c. Also, every vm statistic which depends on 'totalram_pages' will render confusing values, as if system were 'missing' some part of its memory. Impact of this bug: When gigantic hugepages are allocated and sysctl_overcommit_memory == OVERCOMMIT_NEVER. In a such situation, __vm_enough_memory() goes through the mentioned 'allowed' calculation and might end up mistakenly returning -ENOMEM, thus forcing the system to start reclaiming pages earlier than it would be ususal, and this could cause detrimental impact to overall system's performance, depending on the workload. Besides the aforementioned scenario, I can only think of this causing annoyances with memory reports from /proc/meminfo and free(1). [akpm@linux-foundation.org: standardize comment layout] Reported-by: Russ Anderson Signed-off-by: Rafael Aquini Acked-by: Russ Anderson Cc: Andrea Arcangeli Cc: Christoph Lameter Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/hugetlb.c | 8 ++++++++ 1 file changed, 8 insertions(+) (limited to 'mm/hugetlb.c') diff --git a/mm/hugetlb.c b/mm/hugetlb.c index 6402458fee38..bfcf153bc829 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -1111,6 +1111,14 @@ static void __init gather_bootmem_prealloc(void) WARN_ON(page_count(page) != 1); prep_compound_huge_page(page, h->order); prep_new_huge_page(h, page, page_to_nid(page)); + /* + * If we had gigantic hugepages allocated at boot time, we need + * to restore the 'stolen' pages to totalram_pages in order to + * fix confusing memory reports from free(1) and another + * side-effects, like CommitLimit going negative. + */ + if (h->order > (MAX_ORDER - 1)) + totalram_pages += 1 << h->order; } } -- cgit v1.2.3