zram-fix-slot-lock-bit-position-on-big-endian-64-bit.patch removed from -mm tree
The quilt patch titled
Subject: zram: fix slot lock bit position on big-endian 64-bit
has been removed from the -mm tree. Its filename was
zram-fix-slot-lock-bit-position-on-big-endian-64-bit.patch
This patch was dropped because it was merged into the mm-stable branch of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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From: David Carlier <[email protected]>
Subject: zram: fix slot lock bit position on big-endian 64-bit
Date: Mon, 10 Aug 2026 21:22:37 +0100
The slot lock is a bit operation on the whole __lock word, which flags and ac_time alias as two u32s. On little-endian the lock bit lands in the position ZRAM_ENTRY_LOCK reserves in flags, so the aliasing works out. On 64-bit big-endian it lands in ac_time instead: with ZRAM_TRACK_ENTRY_ACTIME enabled, storing the access time from mark_slot_accessed() or slot_free() wipes out the held lock bit, letting another CPU take the same slot lock; an access time value with that bit set makes the slot look locked forever.
Shift the lock bit into the flags half of the word on big-endian 64-bit.
---
drivers/block/zram/zram_drv.c | 6 +++--- drivers/block/zram/zram_drv.h | 14 ++++++++++++++ 2 files changed, 17 insertions(+), 3 deletions(-)
drivers/block/zram/zram_drv.c renamed from drivers/block/zram/zram_drv.c~zram-fix-slot-lock-bit-position-on-big-endian-64-bit +3 -3
@@ -74,7 +74,7 @@ static __must_check bool slot_trylock(st {unsigned long *lock = &zram->table[index].__lock; -if (!test_and_set_bit_lock (ZRAM_ENTRY_LOCK , lock)) { +if (!test_and_set_bit_lock (ZRAM_ENTRY_LOCK_BIT , lock)) {mutex_acquire (&zram->table_lock_map,0 ,1 , _RET_IP_);lock_acquired (&zram->table_lock_map, _RET_IP_);return true;
@@ -88,7 +88,7 @@ static void slot_lock(struct zram *zram,unsigned long *lock = &zram->table[index].__lock;mutex_acquire (&zram->table_lock_map,0 ,0 , _RET_IP_); -wait_on_bit_lock (lock,ZRAM_ENTRY_LOCK ,TASK_UNINTERRUPTIBLE ); +wait_on_bit_lock (lock,ZRAM_ENTRY_LOCK_BIT ,TASK_UNINTERRUPTIBLE );lock_acquired (&zram->table_lock_map, _RET_IP_); }
@@ -97,7 +97,7 @@ static void slot_unlock(struct zram *zraunsigned long *lock = &zram->table[index].__lock;mutex_release (&zram->table_lock_map, _RET_IP_); -clear_and_wake_up_bit (ZRAM_ENTRY_LOCK , lock); +clear_and_wake_up_bit (ZRAM_ENTRY_LOCK_BIT , lock); }static inline bool init_done (struct zram *zram)
drivers/block/zram/zram_drv.h renamed from drivers/block/zram/zram_drv.h~zram-fix-slot-lock-bit-position-on-big-endian-64-bit +14 -0
@@ -15,6 +15,7 @@#ifndef _ZRAM_DRV_H_#define _ZRAM_DRV_H_ +#include <asm/byteorder.h> #include <linux/rwsem.h> #include <linux/zsmalloc.h>
@@ -58,6 +59,19 @@ enum zram_pageflags { };/* +* The slot lock is a bit-wait lock on the whole __lock word, while +* flags and ac_time alias that word as two u32s. The lock bit must +* land in the slot that ZRAM_ENTRY_LOCK reserves in attr.flags; on +* 64-bit big-endian the flags word maps to the upper half of __lock, +* so the bit position has to be shifted up. +*/ +#if defined(CONFIG_64BIT ) && defined(__BIG_ENDIAN) +#define ZRAM_ENTRY_LOCK_BIT (ZRAM_ENTRY_LOCK + 32) +#else +#define ZRAM_ENTRY_LOCK_BIT ZRAM_ENTRY_LOCK +#endif + +/* * Allocated for each disk page. We use bit-lock (ZRAM_ENTRY_LOCK bit * of flags) to save memory. There can be plenty of entries and standard * locking primitives (e.g. mutex) will significantly increase sizeof()
_
Patches currently in -mm which might be from [email protected] are
mm-swap-pm-hibernate-atomically-replace-hibernation-pin.patch