================================================================== BUG: KCSAN: data-race in data_push_tail / number write to 0xffffffff84178db7 of 1 bytes by task 19259 on cpu 1: number+0x836/0xb50 lib/vsprintf.c:556 vsnprintf+0xb6d/0xed0 lib/vsprintf.c:2863 vscnprintf+0x29/0x80 lib/vsprintf.c:2900 printk_sprint kernel/printk/printk.c:2012 [inline] vprintk_store+0x4c1/0x9c0 kernel/printk/printk.c:2115 vprintk_emit+0xca/0x3d0 kernel/printk/printk.c:2157 vprintk_default+0x22/0x30 kernel/printk/printk.c:2185 vprintk+0x15a/0x170 kernel/printk/printk_safe.c:392 printk+0x62/0x87 kernel/printk/printk.c:2216 set_capacity_and_notify+0x15a/0x1c0 block/genhd.c:66 loop_set_size drivers/block/loop.c:257 [inline] loop_configure+0xb58/0xd10 drivers/block/loop.c:1243 lo_ioctl+0x558/0x1210 drivers/block/loop.c:1781 blkdev_ioctl+0x1d0/0x3c0 block/ioctl.c:585 block_ioctl+0x6d/0x80 fs/block_dev.c:1602 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:1069 [inline] __se_sys_ioctl+0xcb/0x140 fs/ioctl.c:1055 __x64_sys_ioctl+0x3f/0x50 fs/ioctl.c:1055 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x3d/0x90 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x44/0xae read to 0xffffffff84178db0 of 8 bytes by task 19285 on cpu 0: data_make_reusable kernel/printk/printk_ringbuffer.c:587 [inline] data_push_tail+0x125/0x460 kernel/printk/printk_ringbuffer.c:672 data_alloc+0xbc/0x2b0 kernel/printk/printk_ringbuffer.c:1043 prb_reserve+0x8f0/0xbc0 kernel/printk/printk_ringbuffer.c:1549 vprintk_store+0x3e9/0x9c0 kernel/printk/printk.c:2105 vprintk_emit+0xca/0x3d0 kernel/printk/printk.c:2157 vprintk_default+0x22/0x30 kernel/printk/printk.c:2185 vprintk+0x15a/0x170 kernel/printk/printk_safe.c:392 printk+0x62/0x87 kernel/printk/printk.c:2216 set_capacity_and_notify+0x15a/0x1c0 block/genhd.c:66 loop_set_size drivers/block/loop.c:257 [inline] loop_configure+0xb58/0xd10 drivers/block/loop.c:1243 lo_ioctl+0x558/0x1210 drivers/block/loop.c:1781 blkdev_ioctl+0x1d0/0x3c0 block/ioctl.c:585 block_ioctl+0x6d/0x80 fs/block_dev.c:1602 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:1069 [inline] __se_sys_ioctl+0xcb/0x140 fs/ioctl.c:1055 __x64_sys_ioctl+0x3f/0x50 fs/ioctl.c:1055 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x3d/0x90 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x44/0xae value changed: 0x0000000100007151 -> 0x742030206d6f7266 Reported by Kernel Concurrency Sanitizer on: CPU: 0 PID: 19285 Comm: syz-executor.2 Tainted: G W 5.14.0-rc1-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 ==================================================================