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Linux 4.8+ compatibility fix for vm stats

vm_node_stat must be used instead of vm_zone_stat. Unfortunately the
old code still compiles potentially leading to silent failure of
arc_evictable_memory()

AKAMAI: CR 3816601: Regression in zfs dropcache test

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Chunwei Chen <tuxoko@gmail.com>
Signed-off-by: Debabrata Banerjee <dbanerje@akamai.com>
Closes #6528
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dbavatar authored and tonyhutter committed Aug 24, 2017
1 parent 4810a10 commit 89950722c627ad4470916c5fe94d200af72817b2
Showing with 28 additions and 0 deletions.
  1. +22 −0 config/kernel-vm_node_stat.m4
  2. +1 −0 config/kernel.m4
  3. +5 −0 module/zfs/arc.c
@@ -0,0 +1,22 @@
dnl #
dnl # 4.8 API change
dnl # kernel vm counters change
dnl #
AC_DEFUN([ZFS_AC_KERNEL_VM_NODE_STAT], [
AC_MSG_CHECKING([whether to use vm_node_stat based fn's])
ZFS_LINUX_TRY_COMPILE([
#include <linux/mm.h>
#include <linux/vmstat.h>
],[
int a __attribute__ ((unused)) = NR_VM_NODE_STAT_ITEMS;
long x __attribute__ ((unused)) =
atomic_long_read(&vm_node_stat[0]);
(void) global_node_page_state(0);
],[
AC_MSG_RESULT(yes)
AC_DEFINE(ZFS_GLOBAL_NODE_PAGE_STATE, 1,
[using global_node_page_state()])
],[
AC_MSG_RESULT(no)
])
])
@@ -120,6 +120,7 @@ AC_DEFUN([ZFS_AC_CONFIG_KERNEL], [
ZFS_AC_KERNEL_RENAME_WANTS_FLAGS
ZFS_AC_KERNEL_HAVE_GENERIC_SETXATTR
ZFS_AC_KERNEL_CURRENT_TIME
ZFS_AC_KERNEL_VM_NODE_STAT

AS_IF([test "$LINUX_OBJ" != "$LINUX"], [
KERNELMAKE_PARAMS="$KERNELMAKE_PARAMS O=$LINUX_OBJ"
@@ -4387,8 +4387,13 @@ arc_evictable_memory(void)
* Scale reported evictable memory in proportion to page cache, cap
* at specified min/max.
*/
#ifdef ZFS_GLOBAL_NODE_PAGE_STATE
uint64_t min = (ptob(global_node_page_state(NR_FILE_PAGES)) / 100) *
zfs_arc_pc_percent;
#else
uint64_t min = (ptob(global_page_state(NR_FILE_PAGES)) / 100) *
zfs_arc_pc_percent;
#endif
min = MAX(arc_c_min, MIN(arc_c_max, min));

if (arc_dirty >= min)

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