[PATCH v9 0/3] scsi: sd: Cleanups and warning fixes in sd_revalidate_disk()

[PATCH v9 0/3] scsi: sd: Cleanups and warning fixes in sd_revalidate_disk()

[Abinash Singh]

Hi all,

Sorry for making mess in previous replies. My gmail app caused that.


This v9 series contains small cleanups and fixes in sd_revalidate_disk().

On Sat, Aug 23, 2025 at 1:17 AM Bart Van Assche wrote:
> From Documentation/process/coding-style.rst:
> These generic allocation functions all emit a stack dump on failure when
> used without __GFP_NOWARN so there is no use in emitting an additional
> failure message when NULL is returned.
>
> Has this example perhaps been followed? I think it is safe to remove
> this sd_printk() statement.

checkpatch.pl also emits the following warning for this code:
  WARNING: Possible unnecessary 'out of memory' message
  #52: FILE: drivers/scsi/sd.c:3716:
  + if (!lim) {
  +     sd_printk(KERN_WARNING, sdkp,

So I agree with Bart — this printk is redundant and should be removed.
In v9, I have split this into a separate patch for clarity.

Summary of changes in this series:
  Removed  the redundant 'out of memory' printk after kmalloc() failure in already existing code.
>     buffer = kmalloc(SD_BUF_SIZE, GFP_KERNEL);
>     if (!buffer) {
>              sd_printk(KERN_WARNING, sdkp, "sd_revalidate_disk: Memory "

  Added Bart Van Assche’s Reviewed-by tag in: [3/3] scsi: sd: make sd_revalidate_disk() return void

Changes since v8:
  - Split removal of the redundant printk into its own patch (1/3),
    instead of keeping it inside the warning fix.
  - Kept the build warning fix and return type change as separate patches.
  - Updated changelogs accordingly.

Thanks

Abinash

Abinash Singh (3):
  scsi: sd: Remove redundant printk after kmalloc failure
  scsi: sd: Fix build warning in sd_revalidate_disk()
  scsi: sd: make sd_revalidate_disk() return void

 drivers/scsi/sd.c | 58 ++++++++++++++++++++++++-----------------------
 1 file changed, 30 insertions(+), 28 deletions(-)

-- 
2.43.0

[PATCH v9 1/3] scsi: sd: Remove redundant printk after kmalloc failure

[Abinash Singh]

The SCSI disk driver prints a warning when kmalloc() fails in
sd_revalidate_disk(). This is redundant because the page allocator
already reports failures unless __GFP_NOWARN is used. Keeping the
extra message only adds noise to the kernel log.

Remove the unnecessary sd_printk() call. Control flow is unchanged.

Fixes: e73aec824703 ("[SCSI] sd: make printing use a common prefix")
Signed-off-by: Abinash Singh <abinashsinghlalotra@gmail.com>
---
 drivers/scsi/sd.c | 5 +----
 1 file changed, 1 insertion(+), 4 deletions(-)

diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c
index 5b8668accf8e..aa9d944e27c5 100644
--- a/drivers/scsi/sd.c
+++ b/drivers/scsi/sd.c
@@ -3712,11 +3712,8 @@ static int sd_revalidate_disk(struct gendisk *disk)
 		goto out;
 
 	buffer = kmalloc(SD_BUF_SIZE, GFP_KERNEL);
-	if (!buffer) {
-		sd_printk(KERN_WARNING, sdkp, "sd_revalidate_disk: Memory "
-			  "allocation failure.\n");
+	if (!buffer)
 		goto out;
-	}
 
 	sd_spinup_disk(sdkp);
 
-- 
2.43.0

Re: [PATCH v9 1/3] scsi: sd: Remove redundant printk after kmalloc failure

[Damien Le Moal]

On 8/25/25 3:02 AM, Abinash Singh wrote:
> The SCSI disk driver prints a warning when kmalloc() fails in
> sd_revalidate_disk(). This is redundant because the page allocator
> already reports failures unless __GFP_NOWARN is used. Keeping the
> extra message only adds noise to the kernel log.
> 
> Remove the unnecessary sd_printk() call. Control flow is unchanged.
> 
> Fixes: e73aec824703 ("[SCSI] sd: make printing use a common prefix")

I do not think this is necessary. Having the message is not a bug.

> Signed-off-by: Abinash Singh <abinashsinghlalotra@gmail.com>

As commented on patch 2, move this patch as patch 2 in the series as it does
not need backporting.

With that, feel free to add:

Reviewed-by: Damien Le Moal <dlemoal@kernel.org>

> ---
>  drivers/scsi/sd.c | 5 +----
>  1 file changed, 1 insertion(+), 4 deletions(-)
> 
> diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c
> index 5b8668accf8e..aa9d944e27c5 100644
> --- a/drivers/scsi/sd.c
> +++ b/drivers/scsi/sd.c
> @@ -3712,11 +3712,8 @@ static int sd_revalidate_disk(struct gendisk *disk)
>  		goto out;
>  
>  	buffer = kmalloc(SD_BUF_SIZE, GFP_KERNEL);
> -	if (!buffer) {
> -		sd_printk(KERN_WARNING, sdkp, "sd_revalidate_disk: Memory "
> -			  "allocation failure.\n");
> +	if (!buffer)
>  		goto out;

Nit: you can return 0 directly here. No need for the goto.

> -	}
>  
>  	sd_spinup_disk(sdkp);
>  


-- 
Damien Le Moal
Western Digital Research

[PATCH v9 2/3] scsi: sd: Fix build warning in sd_revalidate_disk()

[Abinash Singh]

A build warning was triggered due to excessive stack usage in
sd_revalidate_disk():

drivers/scsi/sd.c: In function ‘sd_revalidate_disk.isra’:
drivers/scsi/sd.c:3824:1: warning: the frame size of 1160 bytes is larger than 1024 bytes [-Wframe-larger-than=]

This is caused by a large local struct queue_limits (~400B) allocated
on the stack. Replacing it with a heap allocation using kmalloc()
significantly reduces frame usage. Kernel stack is limited (~8 KB),
and allocating large structs on the stack is discouraged.
As the function already performs heap allocations (e.g. for buffer),
this change fits well.

Signed-off-by: Abinash Singh <abinashsinghlalotra@gmail.com>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
---
 drivers/scsi/sd.c | 50 ++++++++++++++++++++++++++---------------------
 1 file changed, 28 insertions(+), 22 deletions(-)

diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c
index aa9d944e27c5..35856685d7fa 100644
--- a/drivers/scsi/sd.c
+++ b/drivers/scsi/sd.c
@@ -3696,10 +3696,10 @@ static int sd_revalidate_disk(struct gendisk *disk)
 	struct scsi_disk *sdkp = scsi_disk(disk);
 	struct scsi_device *sdp = sdkp->device;
 	sector_t old_capacity = sdkp->capacity;
-	struct queue_limits lim;
-	unsigned char *buffer;
+	struct queue_limits *lim = NULL;
+	unsigned char *buffer = NULL;
 	unsigned int dev_max;
-	int err;
+	int err = 0;
 
 	SCSI_LOG_HLQUEUE(3, sd_printk(KERN_INFO, sdkp,
 				      "sd_revalidate_disk\n"));
@@ -3711,20 +3711,24 @@ static int sd_revalidate_disk(struct gendisk *disk)
 	if (!scsi_device_online(sdp))
 		goto out;
 
+	lim = kmalloc(sizeof(*lim), GFP_KERNEL);
+	if (!lim)
+		goto out;
+
 	buffer = kmalloc(SD_BUF_SIZE, GFP_KERNEL);
 	if (!buffer)
 		goto out;
 
 	sd_spinup_disk(sdkp);
 
-	lim = queue_limits_start_update(sdkp->disk->queue);
+	*lim = queue_limits_start_update(sdkp->disk->queue);
 
 	/*
 	 * Without media there is no reason to ask; moreover, some devices
 	 * react badly if we do.
 	 */
 	if (sdkp->media_present) {
-		sd_read_capacity(sdkp, &lim, buffer);
+		sd_read_capacity(sdkp, lim, buffer);
 		/*
 		 * Some USB/UAS devices return generic values for mode pages
 		 * until the media has been accessed. Trigger a READ operation
@@ -3738,17 +3742,17 @@ static int sd_revalidate_disk(struct gendisk *disk)
 		 * cause this to be updated correctly and any device which
 		 * doesn't support it should be treated as rotational.
 		 */
-		lim.features |= (BLK_FEAT_ROTATIONAL | BLK_FEAT_ADD_RANDOM);
+		lim->features |= (BLK_FEAT_ROTATIONAL | BLK_FEAT_ADD_RANDOM);
 
 		if (scsi_device_supports_vpd(sdp)) {
 			sd_read_block_provisioning(sdkp);
-			sd_read_block_limits(sdkp, &lim);
+			sd_read_block_limits(sdkp, lim);
 			sd_read_block_limits_ext(sdkp);
-			sd_read_block_characteristics(sdkp, &lim);
-			sd_zbc_read_zones(sdkp, &lim, buffer);
+			sd_read_block_characteristics(sdkp, lim);
+			sd_zbc_read_zones(sdkp, lim, buffer);
 		}
 
-		sd_config_discard(sdkp, &lim, sd_discard_mode(sdkp));
+		sd_config_discard(sdkp, lim, sd_discard_mode(sdkp));
 
 		sd_print_capacity(sdkp, old_capacity);
 
@@ -3758,47 +3762,46 @@ static int sd_revalidate_disk(struct gendisk *disk)
 		sd_read_app_tag_own(sdkp, buffer);
 		sd_read_write_same(sdkp, buffer);
 		sd_read_security(sdkp, buffer);
-		sd_config_protection(sdkp, &lim);
+		sd_config_protection(sdkp, lim);
 	}
 
 	/*
 	 * We now have all cache related info, determine how we deal
 	 * with flush requests.
 	 */
-	sd_set_flush_flag(sdkp, &lim);
+	sd_set_flush_flag(sdkp, lim);
 
 	/* Initial block count limit based on CDB TRANSFER LENGTH field size. */
 	dev_max = sdp->use_16_for_rw ? SD_MAX_XFER_BLOCKS : SD_DEF_XFER_BLOCKS;
 
 	/* Some devices report a maximum block count for READ/WRITE requests. */
 	dev_max = min_not_zero(dev_max, sdkp->max_xfer_blocks);
-	lim.max_dev_sectors = logical_to_sectors(sdp, dev_max);
+	lim->max_dev_sectors = logical_to_sectors(sdp, dev_max);
 
 	if (sd_validate_min_xfer_size(sdkp))
-		lim.io_min = logical_to_bytes(sdp, sdkp->min_xfer_blocks);
+		lim->io_min = logical_to_bytes(sdp, sdkp->min_xfer_blocks);
 	else
-		lim.io_min = 0;
+		lim->io_min = 0;
 
 	/*
 	 * Limit default to SCSI host optimal sector limit if set. There may be
 	 * an impact on performance for when the size of a request exceeds this
 	 * host limit.
 	 */
-	lim.io_opt = sdp->host->opt_sectors << SECTOR_SHIFT;
+	lim->io_opt = sdp->host->opt_sectors << SECTOR_SHIFT;
 	if (sd_validate_opt_xfer_size(sdkp, dev_max)) {
-		lim.io_opt = min_not_zero(lim.io_opt,
+		lim->io_opt = min_not_zero(lim->io_opt,
 				logical_to_bytes(sdp, sdkp->opt_xfer_blocks));
 	}
 
 	sdkp->first_scan = 0;
 
 	set_capacity_and_notify(disk, logical_to_sectors(sdp, sdkp->capacity));
-	sd_config_write_same(sdkp, &lim);
-	kfree(buffer);
+	sd_config_write_same(sdkp, lim);
 
-	err = queue_limits_commit_update_frozen(sdkp->disk->queue, &lim);
+	err = queue_limits_commit_update_frozen(sdkp->disk->queue, lim);
 	if (err)
-		return err;
+		goto out;
 
 	/*
 	 * Query concurrent positioning ranges after
@@ -3817,7 +3820,10 @@ static int sd_revalidate_disk(struct gendisk *disk)
 		set_capacity_and_notify(disk, 0);
 
  out:
-	return 0;
+	kfree(buffer);
+	kfree(lim);
+
+	return err;
 }
 
 /**
-- 
2.43.0

Re: [PATCH v9 2/3] scsi: sd: Fix build warning in sd_revalidate_disk()

[Damien Le Moal]

On 8/25/25 3:02 AM, Abinash Singh wrote:
> A build warning was triggered due to excessive stack usage in
> sd_revalidate_disk():
> 
> drivers/scsi/sd.c: In function ‘sd_revalidate_disk.isra’:
> drivers/scsi/sd.c:3824:1: warning: the frame size of 1160 bytes is larger than 1024 bytes [-Wframe-larger-than=]
> 
> This is caused by a large local struct queue_limits (~400B) allocated
> on the stack. Replacing it with a heap allocation using kmalloc()
> significantly reduces frame usage. Kernel stack is limited (~8 KB),
> and allocating large structs on the stack is discouraged.
> As the function already performs heap allocations (e.g. for buffer),
> this change fits well.
> 
> Signed-off-by: Abinash Singh <abinashsinghlalotra@gmail.com>
> Reviewed-by: Bart Van Assche <bvanassche@acm.org>

Looks good, but please move this patch as patch 1 in the series to make sure it
can be easily backported. And please add:

Fixes: 804e498e0496 ("sd: convert to the atomic queue limits API")
Cc: stable@vger.kernel.org

before your signed-off.

-- 
Damien Le Moal
Western Digital Research

[PATCH v9 3/3] scsi: sd: make sd_revalidate_disk() return void

[Abinash Singh]

The sd_revalidate_disk() function currently returns 0 for
both success and memory allocation failure.Since none of its
callers use the return value, this return code is both unnecessary
and potentially misleading.

Change the return type of sd_revalidate_disk() from int to void
and remove all return value handling. This makes the function
semantics clearer and avoids confusion about unused return codes.

Signed-off-by: Abinash Singh <abinashsinghlalotra@gmail.com>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
---
 drivers/scsi/sd.c | 11 +++++------
 1 file changed, 5 insertions(+), 6 deletions(-)

diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c
index 35856685d7fa..b3926c43e700 100644
--- a/drivers/scsi/sd.c
+++ b/drivers/scsi/sd.c
@@ -106,7 +106,7 @@ static void sd_config_discard(struct scsi_disk *sdkp, struct queue_limits *lim,
 		unsigned int mode);
 static void sd_config_write_same(struct scsi_disk *sdkp,
 		struct queue_limits *lim);
-static int  sd_revalidate_disk(struct gendisk *);
+static void  sd_revalidate_disk(struct gendisk *);
 static void sd_unlock_native_capacity(struct gendisk *disk);
 static void sd_shutdown(struct device *);
 static void scsi_disk_release(struct device *cdev);
@@ -3691,7 +3691,7 @@ static void sd_read_block_zero(struct scsi_disk *sdkp)
  *	performs disk spin up, read_capacity, etc.
  *	@disk: struct gendisk we care about
  **/
-static int sd_revalidate_disk(struct gendisk *disk)
+static void sd_revalidate_disk(struct gendisk *disk)
 {
 	struct scsi_disk *sdkp = scsi_disk(disk);
 	struct scsi_device *sdp = sdkp->device;
@@ -3699,7 +3699,7 @@ static int sd_revalidate_disk(struct gendisk *disk)
 	struct queue_limits *lim = NULL;
 	unsigned char *buffer = NULL;
 	unsigned int dev_max;
-	int err = 0;
+	int err;
 
 	SCSI_LOG_HLQUEUE(3, sd_printk(KERN_INFO, sdkp,
 				      "sd_revalidate_disk\n"));
@@ -3709,11 +3709,11 @@ static int sd_revalidate_disk(struct gendisk *disk)
 	 * of the other niceties.
 	 */
 	if (!scsi_device_online(sdp))
-		goto out;
+		return;
 
 	lim = kmalloc(sizeof(*lim), GFP_KERNEL);
 	if (!lim)
-		goto out;
+		return;
 
 	buffer = kmalloc(SD_BUF_SIZE, GFP_KERNEL);
 	if (!buffer)
@@ -3823,7 +3823,6 @@ static int sd_revalidate_disk(struct gendisk *disk)
 	kfree(buffer);
 	kfree(lim);
 
-	return err;
 }
 
 /**
-- 
2.43.0

Re: [PATCH v9 3/3] scsi: sd: make sd_revalidate_disk() return void

[Damien Le Moal]

On 8/25/25 3:02 AM, Abinash Singh wrote:
> The sd_revalidate_disk() function currently returns 0 for
> both success and memory allocation failure.Since none of its
> callers use the return value, this return code is both unnecessary
> and potentially misleading.
> 
> Change the return type of sd_revalidate_disk() from int to void
> and remove all return value handling. This makes the function
> semantics clearer and avoids confusion about unused return codes.
> 
> Signed-off-by: Abinash Singh <abinashsinghlalotra@gmail.com>
> Reviewed-by: Bart Van Assche <bvanassche@acm.org>
> ---
>  drivers/scsi/sd.c | 11 +++++------
>  1 file changed, 5 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c
> index 35856685d7fa..b3926c43e700 100644
> --- a/drivers/scsi/sd.c
> +++ b/drivers/scsi/sd.c
> @@ -106,7 +106,7 @@ static void sd_config_discard(struct scsi_disk *sdkp, struct queue_limits *lim,
>  		unsigned int mode);
>  static void sd_config_write_same(struct scsi_disk *sdkp,
>  		struct queue_limits *lim);
> -static int  sd_revalidate_disk(struct gendisk *);
> +static void  sd_revalidate_disk(struct gendisk *);
>  static void sd_unlock_native_capacity(struct gendisk *disk);
>  static void sd_shutdown(struct device *);
>  static void scsi_disk_release(struct device *cdev);
> @@ -3691,7 +3691,7 @@ static void sd_read_block_zero(struct scsi_disk *sdkp)
>   *	performs disk spin up, read_capacity, etc.
>   *	@disk: struct gendisk we care about
>   **/
> -static int sd_revalidate_disk(struct gendisk *disk)
> +static void sd_revalidate_disk(struct gendisk *disk)
>  {
>  	struct scsi_disk *sdkp = scsi_disk(disk);
>  	struct scsi_device *sdp = sdkp->device;
> @@ -3699,7 +3699,7 @@ static int sd_revalidate_disk(struct gendisk *disk)
>  	struct queue_limits *lim = NULL;
>  	unsigned char *buffer = NULL;
>  	unsigned int dev_max;
> -	int err = 0;
> +	int err;
>  
>  	SCSI_LOG_HLQUEUE(3, sd_printk(KERN_INFO, sdkp,
>  				      "sd_revalidate_disk\n"));
> @@ -3709,11 +3709,11 @@ static int sd_revalidate_disk(struct gendisk *disk)
>  	 * of the other niceties.
>  	 */
>  	if (!scsi_device_online(sdp))
> -		goto out;
> +		return;
>  
>  	lim = kmalloc(sizeof(*lim), GFP_KERNEL);
>  	if (!lim)
> -		goto out;
> +		return;
>  
>  	buffer = kmalloc(SD_BUF_SIZE, GFP_KERNEL);
>  	if (!buffer)

OK. So you can ignore the nit I commented on patch 1.

Looks good.

Reviewed-by: Damien Le Moal <dlemoal@kernel.org>

> @@ -3823,7 +3823,6 @@ static int sd_revalidate_disk(struct gendisk *disk)
>  	kfree(buffer);
>  	kfree(lim);
>  
> -	return err;
>  }
>  
>  /**


-- 
Damien Le Moal
Western Digital Research