diff options
author | Vlastimil Babka <vbabka@suse.cz> | 2017-05-31 09:17:20 +1000 |
---|---|---|
committer | Stephen Rothwell <sfr@canb.auug.org.au> | 2017-06-01 08:39:35 +1000 |
commit | 28edb5a95a41ae0cc8e9686ac937592344182022 (patch) | |
tree | 9f6bc983a4fb033a59ca84a0af68bbc7757d49e4 /mm | |
parent | 365e2e91d7d0f6ea2c536ec282f29158223f546e (diff) |
mm, mempolicy: don't check cpuset seqlock where it doesn't matter
Two wrappers of __alloc_pages_nodemask() are checking
task->mems_allowed_seq themselves to retry allocation that has raced with
a cpuset update. This has been shown to be ineffective in preventing
premature OOM's which can happen in __alloc_pages_slowpath() long before
it returns back to the wrappers to detect the race at that level.
Previous patches have made __alloc_pages_slowpath() more robust, so we can
now simply remove the seqlock checking in the wrappers to prevent further
wrong impression that it can actually help.
Link: http://lkml.kernel.org/r/20170517081140.30654-7-vbabka@suse.cz
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Dimitri Sivanich <sivanich@sgi.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Li Zefan <lizefan@huawei.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'mm')
-rw-r--r-- | mm/mempolicy.c | 16 |
1 files changed, 0 insertions, 16 deletions
diff --git a/mm/mempolicy.c b/mm/mempolicy.c index 047181452040..7d8e56214ac0 100644 --- a/mm/mempolicy.c +++ b/mm/mempolicy.c @@ -1898,12 +1898,9 @@ alloc_pages_vma(gfp_t gfp, int order, struct vm_area_struct *vma, struct mempolicy *pol; struct page *page; int preferred_nid; - unsigned int cpuset_mems_cookie; nodemask_t *nmask; -retry_cpuset: pol = get_vma_policy(vma, addr); - cpuset_mems_cookie = read_mems_allowed_begin(); if (pol->mode == MPOL_INTERLEAVE) { unsigned nid; @@ -1945,8 +1942,6 @@ retry_cpuset: page = __alloc_pages_nodemask(gfp, order, preferred_nid, nmask); mpol_cond_put(pol); out: - if (unlikely(!page && read_mems_allowed_retry(cpuset_mems_cookie))) - goto retry_cpuset; return page; } @@ -1964,23 +1959,15 @@ out: * Allocate a page from the kernel page pool. When not in * interrupt context and apply the current process NUMA policy. * Returns NULL when no page can be allocated. - * - * Don't call cpuset_update_task_memory_state() unless - * 1) it's ok to take cpuset_sem (can WAIT), and - * 2) allocating for current task (not interrupt). */ struct page *alloc_pages_current(gfp_t gfp, unsigned order) { struct mempolicy *pol = &default_policy; struct page *page; - unsigned int cpuset_mems_cookie; if (!in_interrupt() && !(gfp & __GFP_THISNODE)) pol = get_task_policy(current); -retry_cpuset: - cpuset_mems_cookie = read_mems_allowed_begin(); - /* * No reference counting needed for current->mempolicy * nor system default_policy @@ -1992,9 +1979,6 @@ retry_cpuset: policy_node(gfp, pol, numa_node_id()), policy_nodemask(gfp, pol)); - if (unlikely(!page && read_mems_allowed_retry(cpuset_mems_cookie))) - goto retry_cpuset; - return page; } EXPORT_SYMBOL(alloc_pages_current); |