Commit f51bdd2e authored by Shaohua Li's avatar Shaohua Li Committed by Linus Torvalds
Browse files

mm: fix a vmscan warning 



I get the below warning:

  BUG: using smp_processor_id() in preemptible [00000000] code: bash/746
  caller is native_sched_clock+0x37/0x6e
  Pid: 746, comm: bash Tainted: G        W   3.0.0+ #254
  Call Trace:
   [<ffffffff813435c6>] debug_smp_processor_id+0xc2/0xdc
   [<ffffffff8104158d>] native_sched_clock+0x37/0x6e
   [<ffffffff81116219>] try_to_free_mem_cgroup_pages+0x7d/0x270
   [<ffffffff8114f1f8>] mem_cgroup_force_empty+0x24b/0x27a
   [<ffffffff8114ff21>] ? sys_close+0x38/0x138
   [<ffffffff8114ff21>] ? sys_close+0x38/0x138
   [<ffffffff8114f257>] mem_cgroup_force_empty_write+0x17/0x19
   [<ffffffff810c72fb>] cgroup_file_write+0xa8/0xba
   [<ffffffff811522d2>] vfs_write+0xb3/0x138
   [<ffffffff8115241a>] sys_write+0x4a/0x71
   [<ffffffff8114ffd9>] ? sys_close+0xf0/0x138
   [<ffffffff8176deab>] system_call_fastpath+0x16/0x1b

sched_clock() can't be used with preempt enabled.  And we don't need
fast approach to get clock here, so let's use ktime API.

Signed-off-by: default avatarShaohua Li <shaohua.li@intel.com>
Acked-by: default avatarKAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Tested-by: default avatarKAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 7e8aa048

mm/vmscan.c

+8 −8
Original line number Diff line number Diff line
@@ -2283,7 +2283,7 @@ unsigned long mem_cgroup_shrink_node_zone(struct mem_cgroup *mem, 
		.mem_cgroup = mem,

		.memcg_record = rec,

	};

	unsigned long start, end;

	ktime_t start, end;



	sc.gfp_mask = (gfp_mask & GFP_RECLAIM_MASK) |

			(GFP_HIGHUSER_MOVABLE & ~GFP_RECLAIM_MASK);
@@ -2292,7 +2292,7 @@ unsigned long mem_cgroup_shrink_node_zone(struct mem_cgroup *mem, 
						      sc.may_writepage,

						      sc.gfp_mask);



	start = sched_clock();

	start = ktime_get();

	/*

	 * NOTE: Although we can get the priority field, using it

	 * here is not a good idea, since it limits the pages we can scan.
@@ -2301,10 +2301,10 @@ unsigned long mem_cgroup_shrink_node_zone(struct mem_cgroup *mem, 
	 * the priority and make it zero.

	 */

	shrink_zone(0, zone, &sc);

	end = sched_clock();

	end = ktime_get();



	if (rec)

		rec->elapsed += end - start;

		rec->elapsed += ktime_to_ns(ktime_sub(end, start));

	*scanned = sc.nr_scanned;



	trace_mm_vmscan_memcg_softlimit_reclaim_end(sc.nr_reclaimed);
@@ -2319,7 +2319,7 @@ unsigned long try_to_free_mem_cgroup_pages(struct mem_cgroup *mem_cont, 
{

	struct zonelist *zonelist;

	unsigned long nr_reclaimed;

	unsigned long start, end;

	ktime_t start, end;

	int nid;

	struct scan_control sc = {

		.may_writepage = !laptop_mode,
@@ -2337,7 +2337,7 @@ unsigned long try_to_free_mem_cgroup_pages(struct mem_cgroup *mem_cont, 
		.gfp_mask = sc.gfp_mask,

	};



	start = sched_clock();

	start = ktime_get();

	/*

	 * Unlike direct reclaim via alloc_pages(), memcg's reclaim doesn't

	 * take care of from where we get pages. So the node where we start the
@@ -2352,9 +2352,9 @@ unsigned long try_to_free_mem_cgroup_pages(struct mem_cgroup *mem_cont, 
					    sc.gfp_mask);



	nr_reclaimed = do_try_to_free_pages(zonelist, &sc, &shrink);

	end = sched_clock();

	end = ktime_get();

	if (rec)

		rec->elapsed += end - start;

		rec->elapsed += ktime_to_ns(ktime_sub(end, start));



	trace_mm_vmscan_memcg_reclaim_end(nr_reclaimed);

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