The patch titled
Subject: mm: page_alloc: use migrate_disable() in drain_local_pages_wq()
has been added to the -mm tree. Its filename is
mm-page_alloc-use-migrate_disable-in-drain_local_pages_wq.patch
This patch should soon appear at
https://ozlabs.org/~akpm/mmots/broken-out/mm-page_alloc-use-migrate_disable-in-drain_local_pages_wq.patch
and later at
https://ozlabs.org/~akpm/mmotm/broken-out/mm-page_alloc-use-migrate_disable-in-drain_local_pages_wq.patch
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------------------------------------------------------
From: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx>
Subject: mm: page_alloc: use migrate_disable() in drain_local_pages_wq()
drain_local_pages_wq() disables preemption to avoid CPU migration during
CPU hotplug and can't use cpus_read_lock().
Using migrate_disable() works here, too. The scheduler won't take the CPU
offline until the task left the migrate-disable section. The problem with
disabled preemption here is that drain_local_pages() acquires locks which
are turned into sleeping locks on PREEMPT_RT and can't be acquired with
disabled preemption.
Use migrate_disable() in drain_local_pages_wq().
Link: https://lkml.kernel.org/r/20211015210933.viw6rjvo64qtqxn4@xxxxxxxxxxxxx
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/page_alloc.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
--- a/mm/page_alloc.c~mm-page_alloc-use-migrate_disable-in-drain_local_pages_wq
+++ a/mm/page_alloc.c
@@ -3139,9 +3139,9 @@ static void drain_local_pages_wq(struct
* cpu which is alright but we also have to make sure to not move to
* a different one.
*/
- preempt_disable();
+ migrate_disable();
drain_local_pages(drain->zone);
- preempt_enable();
+ migrate_enable();
}
/*
_
Patches currently in -mm which might be from bigeasy@xxxxxxxxxxxxx are
mm-page_alloc-use-migrate_disable-in-drain_local_pages_wq.patch
mm-disable-zsmalloc-on-preempt_rt.patch
documentation-kcov-include-typesh-in-the-example.patch
documentation-kcov-define-ip-in-the-example.patch
kcov-allocate-per-cpu-memory-on-the-relevant-node.patch
kcov-avoid-enabledisable-interrupts-if-in_task.patch
kcov-replace-local_irq_save-with-a-local_lock_t.patch
