[merged mm-stable] percpu-fix-data-race-with-pcpu_nr_empty_pop_pages.patch removed from -mm tree

[merged mm-stable] percpu-fix-data-race-with-pcpu_nr_empty_pop_pages.patch removed from -mm tree

[Andrew Morton]

The quilt patch titled
     Subject: percpu: fix data race with pcpu_nr_empty_pop_pages
has been removed from the -mm tree.  Its filename was
     percpu-fix-data-race-with-pcpu_nr_empty_pop_pages.patch

This patch was dropped because it was merged into the mm-stable branch
of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

------------------------------------------------------
From: Dennis Zhou <dennis@kernel.org>
Subject: percpu: fix data race with pcpu_nr_empty_pop_pages
Date: Mon, 7 Oct 2024 17:19:42 -0700

Fixes the data race by moving the read to be behind the pcpu_lock. This
is okay because the code (initially) above it will not increase the
empty populated page count because it is populating backing pages that
already have allocations served out of them.

Link: https://lkml.kernel.org/r/20241008001942.8114-1-dennis@kernel.org
Reported-by: kernel test robot <oliver.sang@intel.com>
Closes: https://lore.kernel.org/oe-lkp/202407191651.f24e499d-oliver.sang@intel.com
Signed-off-by: Dennis Zhou <dennis@kernel.org>
Cc: Christoph Lameter <cl@linux.com>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/percpu.c |    7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

--- a/mm/percpu.c~percpu-fix-data-race-with-pcpu_nr_empty_pop_pages
+++ a/mm/percpu.c
@@ -1864,6 +1864,10 @@ restart:
 
 area_found:
 	pcpu_stats_area_alloc(chunk, size);
+
+	if (pcpu_nr_empty_pop_pages < PCPU_EMPTY_POP_PAGES_LOW)
+		pcpu_schedule_balance_work();
+
 	spin_unlock_irqrestore(&pcpu_lock, flags);
 
 	/* populate if not all pages are already there */
@@ -1891,9 +1895,6 @@ area_found:
 		mutex_unlock(&pcpu_alloc_mutex);
 	}
 
-	if (pcpu_nr_empty_pop_pages < PCPU_EMPTY_POP_PAGES_LOW)
-		pcpu_schedule_balance_work();
-
 	/* clear the areas and return address relative to base address */
 	for_each_possible_cpu(cpu)
 		memset((void *)pcpu_chunk_addr(chunk, cpu, 0) + off, 0, size);
_

Patches currently in -mm which might be from dennis@kernel.org are