[moderation] [fs?] [mm?] KMSAN: uninit-value in __folio_cancel_dirty

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 02ddfb981de8 Merge tag 'scsi-fixes' of git://git.kernel.or..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=109b10f4580000
kernel config: https://syzkaller.appspot.com/x/.config?x=9dc42c34a3f5c357
dashboard link: https://syzkaller.appspot.com/bug?extid=3bd1e5b3f5e4ae82f527
compiler: Debian clang version 20.1.2 (++20250402124445+58df0ef89dd6-1~exp1~20250402004600.97), Debian LLD 20.1.2
userspace arch: i386
CC: [ak...@linux-foundation.org linux-...@vger.kernel.org linux-...@vger.kernel.org linu...@kvack.org wi...@infradead.org]

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/7dc8afe7520f/disk-02ddfb98.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/3194559250c2/vmlinux-02ddfb98.xz
kernel image: https://storage.googleapis.com/syzbot-assets/86c7c494f08f/bzImage-02ddfb98.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+3bd1e5...@syzkaller.appspotmail.com

=====================================================
BUG: KMSAN: uninit-value in mapping_can_writeback include/linux/backing-dev.h:148 [inline]
BUG: KMSAN: uninit-value in __folio_cancel_dirty+0x300/0x3e0 mm/page-writeback.c:2919
mapping_can_writeback include/linux/backing-dev.h:148 [inline]
__folio_cancel_dirty+0x300/0x3e0 mm/page-writeback.c:2919
folio_cancel_dirty include/linux/pagemap.h:1236 [inline]
truncate_cleanup_folio+0x46c/0x4b0 mm/truncate.c:167
truncate_inode_folio+0x6f/0xa0 mm/truncate.c:175
shmem_undo_range+0x4f2/0x2060 mm/shmem.c:1121
shmem_truncate_range mm/shmem.c:1237 [inline]
shmem_evict_inode+0x232/0xed0 mm/shmem.c:1365
evict+0x6fd/0xd00 fs/inode.c:810
iput_final fs/inode.c:1898 [inline]
iput+0x996/0xdd0 fs/inode.c:1924
dentry_unlink_inode+0x5ce/0x6d0 fs/dcache.c:457
__dentry_kill+0x340/0xbf0 fs/dcache.c:660
dput+0xdd/0x240 fs/dcache.c:902
__fput+0xb0a/0x1040 fs/file_table.c:473
fput_close_sync+0x1e4/0x290 fs/file_table.c:570
__do_sys_close fs/open.c:1581 [inline]
__se_sys_close fs/open.c:1566 [inline]
__ia32_sys_close+0xf0/0x2c0 fs/open.c:1566
ia32_sys_call+0x3106/0x42c0 arch/x86/include/generated/asm/syscalls_32.h:7
do_syscall_32_irqs_on arch/x86/entry/syscall_32.c:83 [inline]
__do_fast_syscall_32+0xb0/0x110 arch/x86/entry/syscall_32.c:306
do_fast_syscall_32+0x38/0x80 arch/x86/entry/syscall_32.c:331
do_SYSENTER_32+0x1f/0x30 arch/x86/entry/syscall_32.c:369
entry_SYSENTER_compat_after_hwframe+0x84/0x8e

Uninit was created at:
__netns_tracker_alloc include/net/net_namespace.h:357 [inline]
sk_alloc+0x5de/0x8a0 net/core/sock.c:2270
__netlink_create net/netlink/af_netlink.c:629 [inline]
__netlink_kernel_create+0x19b/0xcc0 net/netlink/af_netlink.c:2007
netlink_kernel_create include/linux/netlink.h:62 [inline]
iscsi_transport_init+0x355/0x5b0 drivers/scsi/scsi_transport_iscsi.c:4982
do_one_initcall+0x234/0xb60 init/main.c:1257
do_initcall_level+0x166/0x380 init/main.c:1319
do_initcalls+0x1b5/0x350 init/main.c:1335
do_basic_setup+0x22/0x30 init/main.c:1354
kernel_init_freeable+0x2fe/0x4d0 init/main.c:1567
kernel_init+0x2f/0x5e0 init/main.c:1457
ret_from_fork+0x6e/0x90 arch/x86/kernel/process.c:153
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

CPU: 1 UID: 0 PID: 30136 Comm: syz.9.7839 Tainted: G W 6.15.0-rc3-syzkaller-00094-g02ddfb981de8 #0 PREEMPT(undef)
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/19/2025
=====================================================


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[syzbot]

Auto-closing this bug as obsolete.
Crashes did not happen for a while, no reproducer and no activity.