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| author | Linus Torvalds <torvalds@linux-foundation.org> | 2017-01-11 11:15:15 -0800 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2017-01-11 11:15:15 -0800 |
| commit | ba836a6f5ab1243ff5e08a941a2d1de8b31244e1 (patch) | |
| tree | 8925b52d769d0d0170ed7d893d41c5e638917dba /mm/hugetlb.c | |
| parent | cff3b2c4b3d2112eb9bb344e96d3d6aa66f2c13c (diff) | |
| parent | 575b1967e10a1f3038266244d2c7a3ca6b99fed8 (diff) | |
| download | net-ba836a6f5ab1243ff5e08a941a2d1de8b31244e1.tar.gz | |
Merge branch 'akpm' (patches from Andrew)
Merge fixes from Andrew Morton:
"27 fixes.
There are three patches that aren't actually fixes. They're simple
function renamings which are nice-to-have in mainline as ongoing net
development depends on them."
* akpm: (27 commits)
timerfd: export defines to userspace
mm/hugetlb.c: fix reservation race when freeing surplus pages
mm/slab.c: fix SLAB freelist randomization duplicate entries
zram: support BDI_CAP_STABLE_WRITES
zram: revalidate disk under init_lock
mm: support anonymous stable page
mm: add documentation for page fragment APIs
mm: rename __page_frag functions to __page_frag_cache, drop order from drain
mm: rename __alloc_page_frag to page_frag_alloc and __free_page_frag to page_frag_free
mm, memcg: fix the active list aging for lowmem requests when memcg is enabled
mm: don't dereference struct page fields of invalid pages
mailmap: add codeaurora.org names for nameless email commits
signal: protect SIGNAL_UNKILLABLE from unintentional clearing.
mm: pmd dirty emulation in page fault handler
ipc/sem.c: fix incorrect sem_lock pairing
lib/Kconfig.debug: fix frv build failure
mm: get rid of __GFP_OTHER_NODE
mm: fix remote numa hits statistics
mm: fix devm_memremap_pages crash, use mem_hotplug_{begin, done}
ocfs2: fix crash caused by stale lvb with fsdlm plugin
...
Diffstat (limited to 'mm/hugetlb.c')
| -rw-r--r-- | mm/hugetlb.c | 37 |
1 files changed, 28 insertions, 9 deletions
diff --git a/mm/hugetlb.c b/mm/hugetlb.c index 3edb759c5c7d15..c7025c132670a4 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -1773,23 +1773,32 @@ free: } /* - * When releasing a hugetlb pool reservation, any surplus pages that were - * allocated to satisfy the reservation must be explicitly freed if they were - * never used. - * Called with hugetlb_lock held. + * This routine has two main purposes: + * 1) Decrement the reservation count (resv_huge_pages) by the value passed + * in unused_resv_pages. This corresponds to the prior adjustments made + * to the associated reservation map. + * 2) Free any unused surplus pages that may have been allocated to satisfy + * the reservation. As many as unused_resv_pages may be freed. + * + * Called with hugetlb_lock held. However, the lock could be dropped (and + * reacquired) during calls to cond_resched_lock. Whenever dropping the lock, + * we must make sure nobody else can claim pages we are in the process of + * freeing. Do this by ensuring resv_huge_page always is greater than the + * number of huge pages we plan to free when dropping the lock. */ static void return_unused_surplus_pages(struct hstate *h, unsigned long unused_resv_pages) { unsigned long nr_pages; - /* Uncommit the reservation */ - h->resv_huge_pages -= unused_resv_pages; - /* Cannot return gigantic pages currently */ if (hstate_is_gigantic(h)) - return; + goto out; + /* + * Part (or even all) of the reservation could have been backed + * by pre-allocated pages. Only free surplus pages. + */ nr_pages = min(unused_resv_pages, h->surplus_huge_pages); /* @@ -1799,12 +1808,22 @@ static void return_unused_surplus_pages(struct hstate *h, * when the nodes with surplus pages have no free pages. * free_pool_huge_page() will balance the the freed pages across the * on-line nodes with memory and will handle the hstate accounting. + * + * Note that we decrement resv_huge_pages as we free the pages. If + * we drop the lock, resv_huge_pages will still be sufficiently large + * to cover subsequent pages we may free. */ while (nr_pages--) { + h->resv_huge_pages--; + unused_resv_pages--; if (!free_pool_huge_page(h, &node_states[N_MEMORY], 1)) - break; + goto out; cond_resched_lock(&hugetlb_lock); } + +out: + /* Fully uncommit the reservation */ + h->resv_huge_pages -= unused_resv_pages; } |