linux-kernel - [PATCH v2 3/3] bcache: Remove unnecessary select MIN

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Message-Id: <20250614202353.1632957-4-visitorckw@gmail.com>
Date: Sun, 15 Jun 2025 04:23:53 +0800
From: Kuan-Wei Chiu <visitorckw@...il.com>
To: akpm@...ux-foundation.org,
	colyli@...nel.org,
	kent.overstreet@...ux.dev,
	robertpang@...gle.com
Cc: linux-kernel@...r.kernel.org,
	linux-bcache@...r.kernel.org,
	jserv@...s.ncku.edu.tw,
	Kuan-Wei Chiu <visitorckw@...il.com>,
	stable@...r.kernel.org
Subject: [PATCH v2 3/3] bcache: Remove unnecessary select MIN_HEAP

After reverting the transition to the generic min heap library, bcache
no longer depends on MIN_HEAP. The select entry can be removed to
reduce code size and shrink the kernel's attack surface.

This change effectively reverts the bcache-related part of commit
92a8b224b833 ("lib/min_heap: introduce non-inline versions of min heap
API functions").

This is part of a series of changes to address a performance
regression caused by the use of the generic min_heap implementation.

As reported by Robert, bcache now suffers from latency spikes, with
P100 (max) latency increasing from 600 ms to 2.4 seconds every 5
minutes. These regressions degrade bcache's effectiveness as a
low-latency cache layer and lead to frequent timeouts and application
stalls in production environments.

Link: https://lore.kernel.org/lkml/CAJhEC05+0S69z+3+FB2Cd0hD+pCRyWTKLEOsc8BOmH73p1m+KQ@mail.gmail.com
Fixes: 866898efbb25 ("bcache: remove heap-related macros and switch to generic min_heap")
Fixes: 92a8b224b833 ("lib/min_heap: introduce non-inline versions of min heap API functions")
Reported-by: Robert Pang <robertpang@...gle.com>
Closes: https://lore.kernel.org/linux-bcache/CAJhEC06F_AtrPgw2-7CvCqZgeStgCtitbD-ryuPpXQA-JG5XXw@mail.gmail.com
Cc: stable@...r.kernel.org
Signed-off-by: Kuan-Wei Chiu <visitorckw@...il.com>
---
 drivers/md/bcache/Kconfig | 1 -
 1 file changed, 1 deletion(-)

diff --git a/drivers/md/bcache/Kconfig b/drivers/md/bcache/Kconfig
index d4697e79d5a3..b2d10063d35f 100644
--- a/drivers/md/bcache/Kconfig
+++ b/drivers/md/bcache/Kconfig
@@ -5,7 +5,6 @@ config BCACHE
 	select BLOCK_HOLDER_DEPRECATED if SYSFS
 	select CRC64
 	select CLOSURES
-	select MIN_HEAP
 	help
 	Allows a block device to be used as cache for other devices; uses
 	a btree for indexing and the layout is optimized for SSDs.
-- 
2.34.1