The patch titled Subject: bcache: remove unnecessary select MIN_HEAP has been added to the -mm mm-hotfixes-unstable branch. Its filename is bcache-remove-unnecessary-select-min_heap.patch

This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches...

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

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------------------------------------------------------ From: Kuan-Wei Chiu visitorckw@gmail.com Subject: bcache: remove unnecessary select MIN_HEAP Date: Sun, 15 Jun 2025 04:23:53 +0800

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+pCRyWTKLEOsc8BOmH73p1... Link: https://lkml.kernel.org/r/20250614202353.1632957-4-visitorckw@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") Signed-off-by: Kuan-Wei Chiu visitorckw@gmail.com Reported-by: Robert Pang robertpang@google.com Closes: https://lore.kernel.org/linux-bcache/CAJhEC06F_AtrPgw2-7CvCqZgeStgCtitbD-ryu... Acked-by: Coly Li colyli@kernel.org Cc: Ching-Chun (Jim) Huang jserv@ccns.ncku.edu.tw Cc: Kent Overstreet kent.overstreet@linux.dev Cc: stable@vger.kernel.org Signed-off-by: Andrew Morton akpm@linux-foundation.org ---

drivers/md/bcache/Kconfig | 1 - 1 file changed, 1 deletion(-)

--- a/drivers/md/bcache/Kconfig~bcache-remove-unnecessary-select-min_heap +++ a/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. _

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

revert-bcache-update-min_heap_callbacks-to-use-default-builtin-swap.patch revert-bcache-remove-heap-related-macros-and-switch-to-generic-min_heap.patch bcache-remove-unnecessary-select-min_heap.patch lib-math-gcd-use-static-key-to-select-implementation-at-runtime.patch riscv-optimize-gcd-code-size-when-config_riscv_isa_zbb-is-disabled.patch riscv-optimize-gcd-performance-on-risc-v-without-zbb-extension.patch