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author | Aaron Lu <aaron.lu@intel.com> | 2018-12-28 00:34:39 -0800 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2018-12-28 12:11:47 -0800 |
commit | 66f71da9dd38af17dc17209cdde7987d4679a699 (patch) | |
tree | 8f5614b57e7d7a500023247e34c43899d6337c51 /include/linux/swap.h | |
parent | 8b09549c2bfd9f3f8f4cdad74107ef4f4ff9cdd7 (diff) | |
download | linux-stable-66f71da9dd38af17dc17209cdde7987d4679a699.tar.gz linux-stable-66f71da9dd38af17dc17209cdde7987d4679a699.tar.bz2 linux-stable-66f71da9dd38af17dc17209cdde7987d4679a699.zip |
mm/swap: use nr_node_ids for avail_lists in swap_info_struct
Since a2468cc9bfdf ("swap: choose swap device according to numa node"),
avail_lists field of swap_info_struct is changed to an array with
MAX_NUMNODES elements. This made swap_info_struct size increased to 40KiB
and needs an order-4 page to hold it.
This is not optimal in that:
1 Most systems have way less than MAX_NUMNODES(1024) nodes so it
is a waste of memory;
2 It could cause swapon failure if the swap device is swapped on
after system has been running for a while, due to no order-4
page is available as pointed out by Vasily Averin.
Solve the above two issues by using nr_node_ids(which is the actual
possible node number the running system has) for avail_lists instead of
MAX_NUMNODES.
nr_node_ids is unknown at compile time so can't be directly used when
declaring this array. What I did here is to declare avail_lists as zero
element array and allocate space for it when allocating space for
swap_info_struct. The reason why keep using array but not pointer is
plist_for_each_entry needs the field to be part of the struct, so pointer
will not work.
This patch is on top of Vasily Averin's fix commit. I think the use of
kvzalloc for swap_info_struct is still needed in case nr_node_ids is
really big on some systems.
Link: http://lkml.kernel.org/r/20181115083847.GA11129@intel.com
Signed-off-by: Aaron Lu <aaron.lu@intel.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Vasily Averin <vvs@virtuozzo.com>
Cc: Huang Ying <ying.huang@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'include/linux/swap.h')
-rw-r--r-- | include/linux/swap.h | 11 |
1 files changed, 10 insertions, 1 deletions
diff --git a/include/linux/swap.h b/include/linux/swap.h index f9e576a2c188..622025ac1461 100644 --- a/include/linux/swap.h +++ b/include/linux/swap.h @@ -235,7 +235,6 @@ struct swap_info_struct { unsigned long flags; /* SWP_USED etc: see above */ signed short prio; /* swap priority of this type */ struct plist_node list; /* entry in swap_active_head */ - struct plist_node avail_lists[MAX_NUMNODES];/* entry in swap_avail_heads */ signed char type; /* strange name for an index */ unsigned int max; /* extent of the swap_map */ unsigned char *swap_map; /* vmalloc'ed array of usage counts */ @@ -276,6 +275,16 @@ struct swap_info_struct { */ struct work_struct discard_work; /* discard worker */ struct swap_cluster_list discard_clusters; /* discard clusters list */ + struct plist_node avail_lists[0]; /* + * entries in swap_avail_heads, one + * entry per node. + * Must be last as the number of the + * array is nr_node_ids, which is not + * a fixed value so have to allocate + * dynamically. + * And it has to be an array so that + * plist_for_each_* can work. + */ }; #ifdef CONFIG_64BIT |