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Message-ID: <d7c0b48450c70eeb5fd8acd6ecd23593f30dbf1f.1765775954.git.senozhatsky@chromium.org>
Date: Mon, 15 Dec 2025 14:47:11 +0900
From: Sergey Senozhatsky <senozhatsky@...omium.org>
To: Andrew Morton <akpm@...ux-foundation.org>
Cc: Minchan Kim <minchan@...nel.org>,
Brian Geffon <bgeffon@...gle.com>,
David Stevens <stevensd@...gle.com>,
linux-kernel@...r.kernel.org,
linux-mm@...ck.org,
linux-block@...r.kernel.org,
Sergey Senozhatsky <senozhatsky@...omium.org>
Subject: [PATCH 1/3] zram: use u32 for entry ac_time tracking
We can reduce sizeof(zram_table_entry) on 64-bit systems
by converting flags and ac_time to u32. Entry flags fit
into u32, and for ac_time u32 gives us over a century of
entry lifespan (approx 136 years) which is plenty (zram
uses system boot time (seconds)).
In struct zram_table_entry we use bytes aliasing, because
bit-wait API (for slot lock) requires a whole unsigned
long word.
Suggested-by: David Stevens <stevensd@...gle.com>
Signed-off-by: Sergey Senozhatsky <senozhatsky@...omium.org>
---
drivers/block/zram/zram_drv.c | 60 +++++++++++++++++------------------
drivers/block/zram/zram_drv.h | 9 ++++--
2 files changed, 37 insertions(+), 32 deletions(-)
diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
index 67a9e7c005c3..65f99ff3e2e5 100644
--- a/drivers/block/zram/zram_drv.c
+++ b/drivers/block/zram/zram_drv.c
@@ -81,7 +81,7 @@ static void zram_slot_lock_init(struct zram *zram, u32 index)
*/
static __must_check bool zram_slot_trylock(struct zram *zram, u32 index)
{
- unsigned long *lock = &zram->table[index].flags;
+ unsigned long *lock = &zram->table[index].__lock;
if (!test_and_set_bit_lock(ZRAM_ENTRY_LOCK, lock)) {
mutex_acquire(slot_dep_map(zram, index), 0, 1, _RET_IP_);
@@ -94,7 +94,7 @@ static __must_check bool zram_slot_trylock(struct zram *zram, u32 index)
static void zram_slot_lock(struct zram *zram, u32 index)
{
- unsigned long *lock = &zram->table[index].flags;
+ unsigned long *lock = &zram->table[index].__lock;
mutex_acquire(slot_dep_map(zram, index), 0, 0, _RET_IP_);
wait_on_bit_lock(lock, ZRAM_ENTRY_LOCK, TASK_UNINTERRUPTIBLE);
@@ -103,7 +103,7 @@ static void zram_slot_lock(struct zram *zram, u32 index)
static void zram_slot_unlock(struct zram *zram, u32 index)
{
- unsigned long *lock = &zram->table[index].flags;
+ unsigned long *lock = &zram->table[index].__lock;
mutex_release(slot_dep_map(zram, index), _RET_IP_);
clear_and_wake_up_bit(ZRAM_ENTRY_LOCK, lock);
@@ -130,34 +130,33 @@ static void zram_set_handle(struct zram *zram, u32 index, unsigned long handle)
}
static bool zram_test_flag(struct zram *zram, u32 index,
- enum zram_pageflags flag)
+ enum zram_pageflags flag)
{
- return zram->table[index].flags & BIT(flag);
+ return zram->table[index].attr.flags & BIT(flag);
}
static void zram_set_flag(struct zram *zram, u32 index,
- enum zram_pageflags flag)
+ enum zram_pageflags flag)
{
- zram->table[index].flags |= BIT(flag);
+ zram->table[index].attr.flags |= BIT(flag);
}
static void zram_clear_flag(struct zram *zram, u32 index,
- enum zram_pageflags flag)
+ enum zram_pageflags flag)
{
- zram->table[index].flags &= ~BIT(flag);
+ zram->table[index].attr.flags &= ~BIT(flag);
}
static size_t zram_get_obj_size(struct zram *zram, u32 index)
{
- return zram->table[index].flags & (BIT(ZRAM_FLAG_SHIFT) - 1);
+ return zram->table[index].attr.flags & (BIT(ZRAM_FLAG_SHIFT) - 1);
}
-static void zram_set_obj_size(struct zram *zram,
- u32 index, size_t size)
+static void zram_set_obj_size(struct zram *zram, u32 index, size_t size)
{
- unsigned long flags = zram->table[index].flags >> ZRAM_FLAG_SHIFT;
+ unsigned long flags = zram->table[index].attr.flags >> ZRAM_FLAG_SHIFT;
- zram->table[index].flags = (flags << ZRAM_FLAG_SHIFT) | size;
+ zram->table[index].attr.flags = (flags << ZRAM_FLAG_SHIFT) | size;
}
static inline bool zram_allocated(struct zram *zram, u32 index)
@@ -208,14 +207,14 @@ static inline void zram_set_priority(struct zram *zram, u32 index, u32 prio)
* Clear previous priority value first, in case if we recompress
* further an already recompressed page
*/
- zram->table[index].flags &= ~(ZRAM_COMP_PRIORITY_MASK <<
- ZRAM_COMP_PRIORITY_BIT1);
- zram->table[index].flags |= (prio << ZRAM_COMP_PRIORITY_BIT1);
+ zram->table[index].attr.flags &= ~(ZRAM_COMP_PRIORITY_MASK <<
+ ZRAM_COMP_PRIORITY_BIT1);
+ zram->table[index].attr.flags |= (prio << ZRAM_COMP_PRIORITY_BIT1);
}
static inline u32 zram_get_priority(struct zram *zram, u32 index)
{
- u32 prio = zram->table[index].flags >> ZRAM_COMP_PRIORITY_BIT1;
+ u32 prio = zram->table[index].attr.flags >> ZRAM_COMP_PRIORITY_BIT1;
return prio & ZRAM_COMP_PRIORITY_MASK;
}
@@ -225,7 +224,7 @@ static void zram_accessed(struct zram *zram, u32 index)
zram_clear_flag(zram, index, ZRAM_IDLE);
zram_clear_flag(zram, index, ZRAM_PP_SLOT);
#ifdef CONFIG_ZRAM_TRACK_ENTRY_ACTIME
- zram->table[index].ac_time = ktime_get_boottime();
+ zram->table[index].attr.ac_time = (u32)ktime_get_boottime_seconds();
#endif
}
@@ -447,7 +446,7 @@ static void mark_idle(struct zram *zram, ktime_t cutoff)
#ifdef CONFIG_ZRAM_TRACK_ENTRY_ACTIME
is_idle = !cutoff ||
- ktime_after(cutoff, zram->table[index].ac_time);
+ ktime_after(cutoff, zram->table[index].attr.ac_time);
#endif
if (is_idle)
zram_set_flag(zram, index, ZRAM_IDLE);
@@ -461,18 +460,19 @@ static ssize_t idle_store(struct device *dev, struct device_attribute *attr,
const char *buf, size_t len)
{
struct zram *zram = dev_to_zram(dev);
- ktime_t cutoff_time = 0;
+ ktime_t cutoff = 0;
if (!sysfs_streq(buf, "all")) {
/*
* If it did not parse as 'all' try to treat it as an integer
* when we have memory tracking enabled.
*/
- u64 age_sec;
+ u32 age_sec;
- if (IS_ENABLED(CONFIG_ZRAM_TRACK_ENTRY_ACTIME) && !kstrtoull(buf, 0, &age_sec))
- cutoff_time = ktime_sub(ktime_get_boottime(),
- ns_to_ktime(age_sec * NSEC_PER_SEC));
+ if (IS_ENABLED(CONFIG_ZRAM_TRACK_ENTRY_ACTIME) &&
+ !kstrtouint(buf, 0, &age_sec))
+ cutoff = ktime_sub((u32)ktime_get_boottime_seconds(),
+ age_sec);
else
return -EINVAL;
}
@@ -482,10 +482,10 @@ static ssize_t idle_store(struct device *dev, struct device_attribute *attr,
return -EINVAL;
/*
- * A cutoff_time of 0 marks everything as idle, this is the
+ * A cutoff of 0 marks everything as idle, this is the
* "all" behavior.
*/
- mark_idle(zram, cutoff_time);
+ mark_idle(zram, cutoff);
return len;
}
@@ -1588,7 +1588,7 @@ static ssize_t read_block_state(struct file *file, char __user *buf,
if (!zram_allocated(zram, index))
goto next;
- ts = ktime_to_timespec64(zram->table[index].ac_time);
+ ts = ktime_to_timespec64(zram->table[index].attr.ac_time);
copied = snprintf(kbuf + written, count,
"%12zd %12lld.%06lu %c%c%c%c%c%c\n",
index, (s64)ts.tv_sec,
@@ -2013,7 +2013,7 @@ static void zram_slot_free(struct zram *zram, u32 index)
unsigned long handle;
#ifdef CONFIG_ZRAM_TRACK_ENTRY_ACTIME
- zram->table[index].ac_time = 0;
+ zram->table[index].attr.ac_time = 0;
#endif
zram_clear_flag(zram, index, ZRAM_IDLE);
@@ -3286,7 +3286,7 @@ static int __init zram_init(void)
struct zram_table_entry zram_te;
int ret;
- BUILD_BUG_ON(__NR_ZRAM_PAGEFLAGS > sizeof(zram_te.flags) * 8);
+ BUILD_BUG_ON(__NR_ZRAM_PAGEFLAGS > sizeof(zram_te.attr.flags) * 8);
ret = cpuhp_setup_state_multi(CPUHP_ZCOMP_PREPARE, "block/zram:prepare",
zcomp_cpu_up_prepare, zcomp_cpu_dead);
diff --git a/drivers/block/zram/zram_drv.h b/drivers/block/zram/zram_drv.h
index 72fdf66c78ab..48d6861c6647 100644
--- a/drivers/block/zram/zram_drv.h
+++ b/drivers/block/zram/zram_drv.h
@@ -65,10 +65,15 @@ enum zram_pageflags {
*/
struct zram_table_entry {
unsigned long handle;
- unsigned long flags;
+ union {
+ unsigned long __lock;
+ struct attr {
+ u32 flags;
#ifdef CONFIG_ZRAM_TRACK_ENTRY_ACTIME
- ktime_t ac_time;
+ u32 ac_time;
#endif
+ } attr;
+ };
struct lockdep_map dep_map;
};
--
2.52.0.239.gd5f0c6e74e-goog
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