The patch below does not apply to the 5.1-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From b091ac616846a1da75b1f2566b41255ce7f0e0a6 Mon Sep 17 00:00:00 2001

From: Damien Le Moal damien.lemoal@wdc.com Date: Mon, 1 Jul 2019 14:09:17 +0900 Subject: [PATCH] sd_zbc: Fix report zones buffer allocation

During disk scan and revalidation done with sd_revalidate(), the zones of a zoned disk are checked using the helper function blk_revalidate_disk_zones() if a configuration change is detected (change in the number of zones or zone size). The function blk_revalidate_disk_zones() issues report_zones calls that are very large, that is, to obtain zone information for all zones of the disk with a single command. The size of the report zones command buffer necessary for such large request generally is lower than the disk max_hw_sectors and KMALLOC_MAX_SIZE (4MB) and succeeds on boot (no memory fragmentation), but often fail at run time (e.g. hot-plug event). This causes the disk revalidation to fail and the disk capacity to be changed to 0.

This problem can be avoided by using vmalloc() instead of kmalloc() for the buffer allocation. To limit the amount of memory to be allocated, this patch also introduces the arbitrary SD_ZBC_REPORT_MAX_ZONES maximum number of zones to report with a single report zones command. This limit may be lowered further to satisfy the disk max_hw_sectors limit. Finally, to ensure that the vmalloc-ed buffer can always be mapped in a request, the buffer size is further limited to at most queue_max_segments() pages, allowing successful mapping of the buffer even in the worst case scenario where none of the buffer pages are contiguous.

Fixes: 515ce6061312 ("scsi: sd_zbc: Fix sd_zbc_report_zones() buffer allocation") Fixes: e76239a3748c ("block: add a report_zones method") Cc: stable@vger.kernel.org Reviewed-by: Christoph Hellwig hch@lst.de Reviewed-by: Martin K. Petersen martin.petersen@oracle.com Signed-off-by: Damien Le Moal damien.lemoal@wdc.com Signed-off-by: Jens Axboe axboe@kernel.dk

diff --git a/drivers/scsi/sd_zbc.c b/drivers/scsi/sd_zbc.c index ec3764c8f3f1..db16c19e05c4 100644 --- a/drivers/scsi/sd_zbc.c +++ b/drivers/scsi/sd_zbc.c @@ -9,6 +9,8 @@ */

#include <linux/blkdev.h> +#include <linux/vmalloc.h> +#include <linux/sched/mm.h>

#include <asm/unaligned.h>

@@ -50,7 +52,7 @@ static void sd_zbc_parse_report(struct scsi_disk *sdkp, u8 *buf, /** * sd_zbc_do_report_zones - Issue a REPORT ZONES scsi command. * @sdkp: The target disk - * @buf: Buffer to use for the reply + * @buf: vmalloc-ed buffer to use for the reply * @buflen: the buffer size * @lba: Start LBA of the report * @partial: Do partial report @@ -79,7 +81,6 @@ static int sd_zbc_do_report_zones(struct scsi_disk *sdkp, unsigned char *buf, put_unaligned_be32(buflen, &cmd[10]); if (partial) cmd[14] = ZBC_REPORT_ZONE_PARTIAL; - memset(buf, 0, buflen);

result = scsi_execute_req(sdp, cmd, DMA_FROM_DEVICE, buf, buflen, &sshdr, @@ -103,6 +104,53 @@ static int sd_zbc_do_report_zones(struct scsi_disk *sdkp, unsigned char *buf, return 0; }

+/* + * Maximum number of zones to get with one report zones command. + */ +#define SD_ZBC_REPORT_MAX_ZONES 8192U + +/** + * Allocate a buffer for report zones reply. + * @sdkp: The target disk + * @nr_zones: Maximum number of zones to report + * @buflen: Size of the buffer allocated + * + * Try to allocate a reply buffer for the number of requested zones. + * The size of the buffer allocated may be smaller than requested to + * satify the device constraint (max_hw_sectors, max_segments, etc). + * + * Return the address of the allocated buffer and update @buflen with + * the size of the allocated buffer. + */ +static void *sd_zbc_alloc_report_buffer(struct scsi_disk *sdkp, + unsigned int nr_zones, size_t *buflen) +{ + struct request_queue *q = sdkp->disk->queue; + size_t bufsize; + void *buf; + + /* + * Report zone buffer size should be at most 64B times the number of + * zones requested plus the 64B reply header, but should be at least + * SECTOR_SIZE for ATA devices. + * Make sure that this size does not exceed the hardware capabilities. + * Furthermore, since the report zone command cannot be split, make + * sure that the allocated buffer can always be mapped by limiting the + * number of pages allocated to the HBA max segments limit. + */ + nr_zones = min(nr_zones, SD_ZBC_REPORT_MAX_ZONES); + bufsize = roundup((nr_zones + 1) * 64, 512); + bufsize = min_t(size_t, bufsize, + queue_max_hw_sectors(q) << SECTOR_SHIFT); + bufsize = min_t(size_t, bufsize, queue_max_segments(q) << PAGE_SHIFT); + + buf = vzalloc(bufsize); + if (buf) + *buflen = bufsize; + + return buf; +} + /** * sd_zbc_report_zones - Disk report zones operation. * @disk: The target disk @@ -116,30 +164,23 @@ int sd_zbc_report_zones(struct gendisk *disk, sector_t sector, struct blk_zone *zones, unsigned int *nr_zones) { struct scsi_disk *sdkp = scsi_disk(disk); - unsigned int i, buflen, nrz = *nr_zones; + unsigned int i, nrz = *nr_zones; unsigned char *buf; - size_t offset = 0; + size_t buflen = 0, offset = 0; int ret = 0;

if (!sd_is_zoned(sdkp)) /* Not a zoned device */ return -EOPNOTSUPP;

- /* - * Get a reply buffer for the number of requested zones plus a header, - * without exceeding the device maximum command size. For ATA disks, - * buffers must be aligned to 512B. - */ - buflen = min(queue_max_hw_sectors(disk->queue) << 9, - roundup((nrz + 1) * 64, 512)); - buf = kmalloc(buflen, GFP_KERNEL); + buf = sd_zbc_alloc_report_buffer(sdkp, nrz, &buflen); if (!buf) return -ENOMEM;

ret = sd_zbc_do_report_zones(sdkp, buf, buflen, sectors_to_logical(sdkp->device, sector), true); if (ret) - goto out_free_buf; + goto out;

nrz = min(nrz, get_unaligned_be32(&buf[0]) / 64); for (i = 0; i < nrz; i++) { @@ -150,8 +191,8 @@ int sd_zbc_report_zones(struct gendisk *disk, sector_t sector,

*nr_zones = nrz;

-out_free_buf: - kfree(buf); +out: + kvfree(buf);

return ret; } @@ -285,8 +326,6 @@ static int sd_zbc_check_zoned_characteristics(struct scsi_disk *sdkp, return 0; }

-#define SD_ZBC_BUF_SIZE 131072U - /** * sd_zbc_check_zones - Check the device capacity and zone sizes * @sdkp: Target disk @@ -302,22 +341,28 @@ static int sd_zbc_check_zoned_characteristics(struct scsi_disk *sdkp, */ static int sd_zbc_check_zones(struct scsi_disk *sdkp, u32 *zblocks) { + size_t bufsize, buflen; + unsigned int noio_flag; u64 zone_blocks = 0; sector_t max_lba, block = 0; unsigned char *buf; unsigned char *rec; - unsigned int buf_len; - unsigned int list_length; int ret; u8 same;

+ /* Do all memory allocations as if GFP_NOIO was specified */ + noio_flag = memalloc_noio_save(); + /* Get a buffer */ - buf = kmalloc(SD_ZBC_BUF_SIZE, GFP_KERNEL); - if (!buf) - return -ENOMEM; + buf = sd_zbc_alloc_report_buffer(sdkp, SD_ZBC_REPORT_MAX_ZONES, + &bufsize); + if (!buf) { + ret = -ENOMEM; + goto out; + }

/* Do a report zone to get max_lba and the same field */ - ret = sd_zbc_do_report_zones(sdkp, buf, SD_ZBC_BUF_SIZE, 0, false); + ret = sd_zbc_do_report_zones(sdkp, buf, bufsize, 0, false); if (ret) goto out_free;

@@ -353,12 +398,12 @@ static int sd_zbc_check_zones(struct scsi_disk *sdkp, u32 *zblocks) do {

/* Parse REPORT ZONES header */ - list_length = get_unaligned_be32(&buf[0]) + 64; + buflen = min_t(size_t, get_unaligned_be32(&buf[0]) + 64, + bufsize); rec = buf + 64; - buf_len = min(list_length, SD_ZBC_BUF_SIZE);

/* Parse zone descriptors */ - while (rec < buf + buf_len) { + while (rec < buf + buflen) { u64 this_zone_blocks = get_unaligned_be64(&rec[8]);

if (zone_blocks == 0) { @@ -374,8 +419,8 @@ static int sd_zbc_check_zones(struct scsi_disk *sdkp, u32 *zblocks) }

if (block < sdkp->capacity) { - ret = sd_zbc_do_report_zones(sdkp, buf, SD_ZBC_BUF_SIZE, - block, true); + ret = sd_zbc_do_report_zones(sdkp, buf, bufsize, block, + true); if (ret) goto out_free; } @@ -406,7 +451,8 @@ static int sd_zbc_check_zones(struct scsi_disk *sdkp, u32 *zblocks) }

out_free: - kfree(buf); + memalloc_noio_restore(noio_flag); + kvfree(buf);

return ret; }