[nacked] mm-page_alloc-add-scheduling-point-to-free_unref_page_list.patch removed from -mm tree

[nacked] mm-page_alloc-add-scheduling-point-to-free_unref_page_list.patch removed from -mm tree

[Andrew Morton]

The patch titled
     Subject: mm/page_alloc: add scheduling point to free_unref_page_list
has been removed from the -mm tree.  Its filename was
     mm-page_alloc-add-scheduling-point-to-free_unref_page_list.patch

This patch was dropped because it was nacked

------------------------------------------------------
From: wangjianxing <wangjianxing@loongson.cn>
Subject: mm/page_alloc: add scheduling point to free_unref_page_list

Freeing a large list of pages may cause rcu_sched starvatoin on
non-preemptible kernels

rcu: rcu_sched kthread starved for 5359 jiffies! g454793 f0x0
RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=19
[...]
Call Trace:
  free_unref_page_list+0x19c/0x270
  release_pages+0x3cc/0x498
  tlb_flush_mmu_free+0x44/0x70
  zap_pte_range+0x450/0x738
  unmap_page_range+0x108/0x240
  unmap_vmas+0x74/0xf0
  unmap_region+0xb0/0x120
  do_munmap+0x264/0x438
  vm_munmap+0x58/0xa0
  sys_munmap+0x10/0x20
  syscall_common+0x24/0x38

Link: https://lkml.kernel.org/r/20220302013825.2290315-1-wangjianxing@loongson.cn
Signed-off-by: wangjianxing <wangjianxing@loongson.cn>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/page_alloc.c |    3 +++
 1 file changed, 3 insertions(+)

--- a/mm/page_alloc.c~mm-page_alloc-add-scheduling-point-to-free_unref_page_list
+++ a/mm/page_alloc.c
@@ -3479,6 +3479,9 @@ void free_unref_page_list(struct list_he
 		 */
 		if (++batch_count == SWAP_CLUSTER_MAX) {
 			local_unlock_irqrestore(&pagesets.lock, flags);
+
+			cond_resched();
+
 			batch_count = 0;
 			local_lock_irqsave(&pagesets.lock, flags);
 		}
_

Patches currently in -mm which might be from wangjianxing@loongson.cn are