From: Connor Williamson Date: Mon, 15 Jun 2026 13:07:15 +0000 (+0000) Subject: block: remove redundant GD_NEED_PART_SCAN in add_disk_final() X-Git-Tag: v7.2-rc3~15^2 X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=181bb9c9eae4f69fe510a62a42c2932d0314a800;p=thirdparty%2Fkernel%2Flinux.git block: remove redundant GD_NEED_PART_SCAN in add_disk_final() add_disk_final() sets GD_NEED_PART_SCAN before calling bdev_add(), then calls disk_scan_partitions() which sets the flag itself. The early set is redundant and introduces a race. Between bdev_add() and disk_scan_partitions(), concurrent openers (multipathd, blkid, LVM) see the flag in blkdev_get_whole() and trigger bdev_disk_changed(). When disk_scan_partitions() then runs, it calls bdev_disk_changed() again, dropping the partitions the concurrent opener already created before re-adding them, which can result in transient partition disappearances. The race is observable by inserting an msleep() between bdev_add() and disk_scan_partitions() while running concurrent open() calls during device bind. Without artificial delay, it manifests under scheduling pressure during boot on systems with aggressive device scanners (multipathd, systemd-udevd). Therefore, do not set GD_NEED_PART_SCAN in add_disk_final(). Other GD_NEED_PART_SCAN consumers (blkdev_get_whole(), sd_need_revalidate()) should not be affected as the flag is set internally by disk_scan_partitions(). The retry-on-next-open intention from commit e5cfefa97bcc ("block: fix scan partition for exclusively open device again") should also not be affected as the early return paths in disk_scan_partitions() should be unreachable at device registration time (bd_holder is NULL and open_partitions is zero). Fixes: e5cfefa97bcc ("block: fix scan partition for exclusively open device again") Cc: stable@vger.kernel.org Signed-off-by: Connor Williamson Reviewed-by: Christoph Hellwig Link: https://patch.msgid.link/20260615130715.53693-1-connordw@amazon.com Signed-off-by: Jens Axboe --- diff --git a/block/genhd.c b/block/genhd.c index 30ac0ffe6517..df2c3c69b467 100644 --- a/block/genhd.c +++ b/block/genhd.c @@ -407,10 +407,6 @@ static void add_disk_final(struct gendisk *disk) struct device *ddev = disk_to_dev(disk); if (!(disk->flags & GENHD_FL_HIDDEN)) { - /* Make sure the first partition scan will be proceed */ - if (get_capacity(disk) && disk_has_partscan(disk)) - set_bit(GD_NEED_PART_SCAN, &disk->state); - bdev_add(disk->part0, ddev->devt); if (get_capacity(disk)) disk_scan_partitions(disk, BLK_OPEN_READ);