From ee8eb9a5fe86332c6c6163a2322376f960026596 Mon Sep 17 00:00:00 2001 From: Joel Savitz Date: Wed, 1 Apr 2020 21:09:44 -0700 Subject: [PATCH] mm/page_alloc: increase default min_free_kbytes bound Currently, the vm.min_free_kbytes sysctl value is capped at a hardcoded 64M in init_per_zone_wmark_min (unless it is overridden by khugepaged initialization). This value has not been modified since 2005, and enterprise-grade systems now frequently have hundreds of GB of RAM and multiple 10, 40, or even 100 GB NICs. We have seen page allocation failures on heavily loaded systems related to NIC drivers. These issues were resolved by an increase to vm.min_free_kbytes. This patch increases the hardcoded value by a factor of 4 as a temporary solution. Further work to make the calculation of vm.min_free_kbytes more consistent throughout the kernel would be desirable. As an example of the inconsistency of the current method, this value is recalculated by init_per_zone_wmark_min() in the case of memory hotplug which will override the value set by set_recommended_min_free_kbytes() called during khugepaged initialization even if khugepaged remains enabled, however an on/off toggle of khugepaged will then recalculate and set the value via set_recommended_min_free_kbytes(). Signed-off-by: Joel Savitz Signed-off-by: Andrew Morton Reviewed-by: Andrew Morton Cc: Rafael Aquini Link: http://lkml.kernel.org/r/20200220150103.5183-1-jsavitz@redhat.com Signed-off-by: Linus Torvalds --- mm/page_alloc.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 7c30f90c3ef4..fb0b3ff17571 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -7868,8 +7868,8 @@ int __meminit init_per_zone_wmark_min(void) min_free_kbytes = new_min_free_kbytes; if (min_free_kbytes < 128) min_free_kbytes = 128; - if (min_free_kbytes > 65536) - min_free_kbytes = 65536; + if (min_free_kbytes > 262144) + min_free_kbytes = 262144; } else { pr_warn("min_free_kbytes is not updated to %d because user defined value %d is preferred\n", new_min_free_kbytes, user_min_free_kbytes); -- 2.11.0