linux-kernel - Re: [PATCH 1/3] zram: use u32 for entry ac

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Message-ID: <5dm7qshgxenr6urnd4mdis75r6zpk2rlzcey4svjsp6m4jvnqw@iq4myzyiwm6u>
Date: Thu, 15 Jan 2026 12:13:46 +0900
From: Sergey Senozhatsky <senozhatsky@...omium.org>
To: Chris Mason <clm@...a.com>
Cc: Sergey Senozhatsky <senozhatsky@...omium.org>, 
	Andrew Morton <akpm@...ux-foundation.org>, 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
Subject: Re: [PATCH 1/3] zram: use u32 for entry ac_time tracking

On (26/01/14 04:45), Chris Mason wrote:
> > @@ -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,
> >  			ts.tv_nsec / NSEC_PER_USEC,
> 
> ktime_to_timespec64() is defined as ns_to_timespec64(), which expects
> nanoseconds.  Since ac_time now stores seconds, will this produce
> incorrect output?
> 
> For example, if ac_time is 3600 (representing 1 hour of uptime),
> ns_to_timespec64(3600) would compute ts.tv_sec = 3600 / 1000000000 = 0
> and ts.tv_nsec = 3600, resulting in "0.000003" instead of "3600.000000".

Good catch.

I think it simply should be like this now (I don't think anyone uses
this function tho):

---
 drivers/block/zram/zram_drv.c | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
index cc51aa8b6181..912711faa4e4 100644
--- a/drivers/block/zram/zram_drv.c
+++ b/drivers/block/zram/zram_drv.c
@@ -1579,11 +1579,9 @@ static ssize_t read_block_state(struct file *file, char __user *buf,
 		if (!slot_allocated(zram, index))
 			goto next;
 
-		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,
-			ts.tv_nsec / NSEC_PER_USEC,
+			"%12zd %12u.%06lu %c%c%c%c%c%c\n",
+			index, zram->table[index].attr.ac_time, 0,
 			test_slot_flag(zram, index, ZRAM_SAME) ? 's' : '.',
 			test_slot_flag(zram, index, ZRAM_WB) ? 'w' : '.',
 			test_slot_flag(zram, index, ZRAM_HUGE) ? 'h' : '.',
-- 
2.52.0.457.g6b5491de43-goog