| Message ID | 20250416082405.20988-1-zhangtianyang@loongson.cn (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | mm/page_alloc.c: Avoid infinite retries caused by cpuset race | expand |
diff --git a/mm/page_alloc.c b/mm/page_alloc.c index fd6b865cb1ab..1e82f5214a42 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -4530,6 +4530,14 @@ __alloc_pages_slowpath(gfp_t gfp_mask, unsigned int order, } retry: + /* + * Deal with possible cpuset update races or zonelist updates to avoid + * infinite retries. + */ + if (check_retry_cpuset(cpuset_mems_cookie, ac) || + check_retry_zonelist(zonelist_iter_cookie)) + goto restart; + /* Ensure kswapd doesn't accidentally go to sleep as long as we loop */ if (alloc_flags & ALLOC_KSWAPD) wake_all_kswapds(order, gfp_mask, ac);
__alloc_pages_slowpath has no change detection for ac->nodemask in the part of retry path, while cpuset can modify it in parallel. For some processes that set mempolicy as MPOL_BIND, this results ac->nodemask changes, and then the should_reclaim_retry will judge based on the latest nodemask and jump to retry, while the get_page_from_freelist only traverses the zonelist from ac->preferred_zoneref, which selected by a expired nodemask and may cause infinite retries in some cases cpu 64: __alloc_pages_slowpath { /* ..... */ retry: /* ac->nodemask = 0x1, ac->preferred->zone->nid = 1 */ if (alloc_flags & ALLOC_KSWAPD) wake_all_kswapds(order, gfp_mask, ac); /* cpu 1: cpuset_write_resmask update_nodemask update_nodemasks_hier update_tasks_nodemask mpol_rebind_task mpol_rebind_policy mpol_rebind_nodemask // mempolicy->nodes has been modified, // which ac->nodemask point to */ /* ac->nodemask = 0x3, ac->preferred->zone->nid = 1 */ if (should_reclaim_retry(gfp_mask, order, ac, alloc_flags, did_some_progress > 0, &no_progress_loops)) goto retry; } Simultaneously starting multiple cpuset01 from LTP can quickly reproduce this issue on a multi node server when the maximum memory pressure is reached and the swap is enabled Signed-off-by: Tianyang Zhang <zhangtianyang@loongson.cn> --- mm/page_alloc.c | 8 ++++++++ 1 file changed, 8 insertions(+)