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Wed, 14 Jan 2026 19:13:52 -0800 (PST) Received: from google.com ([2a00:79e0:2031:6:36c2:991a:5236:1fe5]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-2a3e3c5ce06sm235752335ad.44.2026.01.14.19.13.48 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 14 Jan 2026 19:13:51 -0800 (PST) Date: Thu, 15 Jan 2026 12:13:46 +0900 From: Sergey Senozhatsky To: Chris Mason Cc: Sergey Senozhatsky , Andrew Morton , Minchan Kim , Brian Geffon , David Stevens , linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-block@vger.kernel.org Subject: Re: [PATCH 1/3] zram: use u32 for entry ac_time tracking Message-ID: <5dm7qshgxenr6urnd4mdis75r6zpk2rlzcey4svjsp6m4jvnqw@iq4myzyiwm6u> References: <20260114124522.1326519-1-clm@meta.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260114124522.1326519-1-clm@meta.com> X-Stat-Signature: 7igs9co9qxkk1c1refag6eatfwufudrh X-Rspamd-Queue-Id: 9415080009 X-Rspam-User: X-Rspamd-Server: rspam02 X-HE-Tag: 1768446833-467502 X-HE-Meta: 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 zovgEy6c XekrRzi1gkt1su/99A95FUPX/Fcbtcobnz/P4dlCFoongYkpMfmryrk7UGEcR2y8tLZxp9XcYtynjix+DzkvdLNYp8mAOmGREQhoZ3c1LGmOBBp+HjMKMyXTMTgFD3ypgsQC/HsF8exoeHtDwR6CP55SO5I06WrTPKLrrFAiX4ZzCkJqfwekAl1XXNOgkSWt/Rff4JIJBw82kefv7GFrCjt6xsfeXi6h0k039tywVgjW5hmugwABZtppYsA9TW7OmaUcBJtt/2c4GAGlziFNV9Vrd4zDR3M0EKZHEAS+pf3RC14e/t7JYmFDNPaDqN/+pn2wOYTrnlBItK5lSkBKTV5UR1dlgE2C57JCLZnC69L0GgzkqWMFw0YP/Ifp3wBJIXWkqulGSFIDMwX9PuJkmqiDcrd7ykmiRJsUwA1SaosTkflRkcTp2PiXfFCARTxPINOIr1xDnduVgj8oOKdJrZvRoLOSqPzdYXh1geimASc5srjo= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: 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