diff options
| author | Heiko Carstens <heiko.carstens@de.ibm.com> | 2017-08-02 23:32:12 +0300 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2017-08-03 03:16:11 +0300 |
| commit | 167d0f258fedbfc859ad4105b1ea236818d41bdd (patch) | |
| tree | fcdf1d2a6d4e977c3e86895e3a46395004ae1899 /mm | |
| parent | b0ba2d0faf6520dd0e534a9410114e043e9ab084 (diff) | |
| download | linux-167d0f258fedbfc859ad4105b1ea236818d41bdd.tar.xz | |
mm: take memory hotplug lock within numa_zonelist_order_handler()
Andre Wild reported the following warning:
WARNING: CPU: 2 PID: 1205 at kernel/cpu.c:240 lockdep_assert_cpus_held+0x4c/0x60
Modules linked in:
CPU: 2 PID: 1205 Comm: bash Not tainted 4.13.0-rc2-00022-gfd2b2c57ec20 #10
Hardware name: IBM 2964 N96 702 (z/VM 6.4.0)
task: 00000000701d8100 task.stack: 0000000073594000
Krnl PSW : 0704f00180000000 0000000000145e24 (lockdep_assert_cpus_held+0x4c/0x60)
...
Call Trace:
lockdep_assert_cpus_held+0x42/0x60)
stop_machine_cpuslocked+0x62/0xf0
build_all_zonelists+0x92/0x150
numa_zonelist_order_handler+0x102/0x150
proc_sys_call_handler.isra.12+0xda/0x118
proc_sys_write+0x34/0x48
__vfs_write+0x3c/0x178
vfs_write+0xbc/0x1a0
SyS_write+0x66/0xc0
system_call+0xc4/0x2b0
locks held by bash/1205:
#0: (sb_writers#4){.+.+.+}, at: vfs_write+0xa6/0x1a0
#1: (zl_order_mutex){+.+...}, at: numa_zonelist_order_handler+0x44/0x150
#2: (zonelists_mutex){+.+...}, at: numa_zonelist_order_handler+0xf4/0x150
Last Breaking-Event-Address:
lockdep_assert_cpus_held+0x48/0x60
This can be easily triggered with e.g.
echo n > /proc/sys/vm/numa_zonelist_order
In commit 3f906ba23689a ("mm/memory-hotplug: switch locking to a percpu
rwsem") memory hotplug locking was changed to fix a potential deadlock.
This also switched the stop_machine() invocation within
build_all_zonelists() to stop_machine_cpuslocked() which now expects
that online cpus are locked when being called.
This assumption is not true if build_all_zonelists() is being called
from numa_zonelist_order_handler().
In order to fix this simply add a mem_hotplug_begin()/mem_hotplug_done()
pair to numa_zonelist_order_handler().
Link: http://lkml.kernel.org/r/20170726111738.38768-1-heiko.carstens@de.ibm.com
Fixes: 3f906ba23689a ("mm/memory-hotplug: switch locking to a percpu rwsem")
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Reported-by: Andre Wild <wild@linux.vnet.ibm.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm')
| -rw-r--r-- | mm/page_alloc.c | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 6d30e914afb6..fc32aa81f359 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -4891,9 +4891,11 @@ int numa_zonelist_order_handler(struct ctl_table *table, int write, NUMA_ZONELIST_ORDER_LEN); user_zonelist_order = oldval; } else if (oldval != user_zonelist_order) { + mem_hotplug_begin(); mutex_lock(&zonelists_mutex); build_all_zonelists(NULL, NULL); mutex_unlock(&zonelists_mutex); + mem_hotplug_done(); } } out: |