linux-kernel - [PATCH 04/12] mm: compaction: clean up comment for sched contention

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Message-ID: <20220418141253.24298-5-linmiaohe@huawei.com>
Date:   Mon, 18 Apr 2022 22:12:45 +0800
From:   Miaohe Lin <linmiaohe@...wei.com>
To:     <akpm@...ux-foundation.org>
CC:     <vbabka@...e.cz>, <pintu@...eaurora.org>,
        <charante@...eaurora.org>, <linux-mm@...ck.org>,
        <linux-kernel@...r.kernel.org>, <linmiaohe@...wei.com>
Subject: [PATCH 04/12] mm: compaction: clean up comment for sched contention

Since commit cf66f0700c8f ("mm, compaction: do not consider a need to
reschedule as contention"), async compaction won't abort when scheduling
is needed. Correct the relevant comment accordingly.

Signed-off-by: Miaohe Lin <linmiaohe@...wei.com>
---
 mm/compaction.c | 11 ++++-------
 mm/internal.h   |  2 +-
 2 files changed, 5 insertions(+), 8 deletions(-)

diff --git a/mm/compaction.c b/mm/compaction.c
index ee2ddf77191f..e839b26fb3d8 100644
--- a/mm/compaction.c
+++ b/mm/compaction.c
@@ -513,15 +513,12 @@ static bool compact_lock_irqsave(spinlock_t *lock, unsigned long *flags,
  * very heavily contended. The lock should be periodically unlocked to avoid
  * having disabled IRQs for a long time, even when there is nobody waiting on
  * the lock. It might also be that allowing the IRQs will result in
- * need_resched() becoming true. If scheduling is needed, async compaction
- * aborts. Sync compaction schedules.
+ * need_resched() becoming true. If scheduling is needed, compaction schedules.
  * Either compaction type will also abort if a fatal signal is pending.
  * In either case if the lock was locked, it is dropped and not regained.
  *
- * Returns true if compaction should abort due to fatal signal pending, or
- *		async compaction due to need_resched()
- * Returns false when compaction can continue (sync compaction might have
- *		scheduled)
+ * Returns true if compaction should abort due to fatal signal pending.
+ * Returns false when compaction can continue.
  */
 static bool compact_unlock_should_abort(spinlock_t *lock,
 		unsigned long flags, bool *locked, struct compact_control *cc)
@@ -574,7 +571,7 @@ static unsigned long isolate_freepages_block(struct compact_control *cc,
 		/*
 		 * Periodically drop the lock (if held) regardless of its
 		 * contention, to give chance to IRQs. Abort if fatal signal
-		 * pending or async compaction detects need_resched()
+		 * pending.
 		 */
 		if (!(blockpfn % SWAP_CLUSTER_MAX)
 		    && compact_unlock_should_abort(&cc->zone->lock, flags,
diff --git a/mm/internal.h b/mm/internal.h
index 48eb2d24fcd2..70cc61af06de 100644
--- a/mm/internal.h
+++ b/mm/internal.h
@@ -403,7 +403,7 @@ struct compact_control {
 	bool direct_compaction;		/* False from kcompactd or /proc/... */
 	bool proactive_compaction;	/* kcompactd proactive compaction */
 	bool whole_zone;		/* Whole zone should/has been scanned */
-	bool contended;			/* Signal lock or sched contention */
+	bool contended;			/* Signal lock contention */
 	bool rescan;			/* Rescanning the same pageblock */
 	bool alloc_contig;		/* alloc_contig_range allocation */
 };
-- 
2.23.0