+ lib-flex_proportionsc-remove-local_irq_ops-in-fprop_new_period.patch added to mm-nonmm-unstable branch

+ lib-flex_proportionsc-remove-local_irq_ops-in-fprop_new_period.patch added to mm-nonmm-unstable branch

[Andrew Morton]

The patch titled
     Subject: lib/flex_proportions.c: remove local_irq_ops in fprop_new_period()
has been added to the -mm mm-nonmm-unstable branch.  Its filename is
     lib-flex_proportionsc-remove-local_irq_ops-in-fprop_new_period.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/lib-flex_proportionsc-remove-local_irq_ops-in-fprop_new_period.patch

This patch will later appear in the mm-nonmm-unstable branch at
    git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

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------------------------------------------------------
From: wuchi <wuchi.zero@gmail.com>
Subject: lib/flex_proportions.c: remove local_irq_ops in fprop_new_period()
Date: Sat, 4 Jun 2022 21:15:02 +0800

commit e78d4833c03e28> "lib: Fix possible deadlock in flexible proportion
code" adds the local_irq_ops because percpu_counter_{sum |add} ops'lock
can cause deadlock by interrupts.  Now percpu_counter _{sum|add} ops use
raw_spin_(un)lock_irq*, so revert the commit and resolve the conflict.

Link: https://lkml.kernel.org/r/20220604131502.5190-1-wuchi.zero@gmail.com
Signed-off-by: wuchi <wuchi.zero@gmail.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Christoph Hellwig <hch@lst.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 lib/flex_proportions.c |   10 ++--------
 1 file changed, 2 insertions(+), 8 deletions(-)

--- a/lib/flex_proportions.c~lib-flex_proportionsc-remove-local_irq_ops-in-fprop_new_period
+++ a/lib/flex_proportions.c
@@ -63,18 +63,13 @@ void fprop_global_destroy(struct fprop_g
  */
 bool fprop_new_period(struct fprop_global *p, int periods)
 {
-	s64 events;
-	unsigned long flags;
+	s64 events = percpu_counter_sum(&p->events);
 
-	local_irq_save(flags);
-	events = percpu_counter_sum(&p->events);
 	/*
 	 * Don't do anything if there are no events.
 	 */
-	if (events <= 1) {
-		local_irq_restore(flags);
+	if (events <= 1)
 		return false;
-	}
 	write_seqcount_begin(&p->sequence);
 	if (periods < 64)
 		events -= events >> periods;
@@ -82,7 +77,6 @@ bool fprop_new_period(struct fprop_globa
 	percpu_counter_add(&p->events, -events);
 	p->period += periods;
 	write_seqcount_end(&p->sequence);
-	local_irq_restore(flags);
 
 	return true;
 }
_

Patches currently in -mm which might be from wuchi.zero@gmail.com are

lib-flex_proportionsc-remove-local_irq_ops-in-fprop_new_period.patch