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BUG: KMSAN: uninit-value in copyout lib/iov_iter.c:140 [inline]
BUG: KMSAN: uninit-value in copy_page_to_iter_iovec lib/iov_iter.c:212 [inline]
BUG: KMSAN: uninit-value in copy_page_to_iter+0x754/0x1b70 lib/iov_iter.c:716
CPU: 1 PID: 21162 Comm: blkid Not tainted 4.17.0+ #3
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x185/0x1d0 lib/dump_stack.c:113
 kmsan_report+0x149/0x260 mm/kmsan/kmsan.c:1084
 kmsan_internal_check_memory+0x179/0x1e0 mm/kmsan/kmsan.c:1196
 kmsan_copy_to_user+0x75/0x160 mm/kmsan/kmsan.c:1219
 copyout lib/iov_iter.c:140 [inline]
 copy_page_to_iter_iovec lib/iov_iter.c:212 [inline]
 copy_page_to_iter+0x754/0x1b70 lib/iov_iter.c:716
 generic_file_buffered_read mm/filemap.c:2185 [inline]
 generic_file_read_iter+0x2ef8/0x44d0 mm/filemap.c:2362
 blkdev_read_iter+0x20d/0x280 fs/block_dev.c:1930
 call_read_iter include/linux/fs.h:1778 [inline]
 new_sync_read fs/read_write.c:406 [inline]
 __vfs_read+0x775/0x9d0 fs/read_write.c:418
 vfs_read+0x36c/0x6b0 fs/read_write.c:452
 ksys_read fs/read_write.c:578 [inline]
 __do_sys_read fs/read_write.c:588 [inline]
 __se_sys_read fs/read_write.c:586 [inline]
 __x64_sys_read+0x1bf/0x3e0 fs/read_write.c:586
 do_syscall_64+0x15b/0x230 arch/x86/entry/common.c:287
 entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x7f6229003310
RSP: 002b:00007ffc459d0268 EFLAGS: 00000246 ORIG_RAX: 0000000000000000
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f6229003310
RDX: 0000000000000561 RSI: 00000000023d2128 RDI: 0000000000000003
RBP: 00000000023d2100 R08: 0000000000000018 R09: 0000000001680000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000023cb030
R13: 0000000000000561 R14: 00000000023cb080 R15: 00000000023d2118

Uninit was created at:
 kmsan_save_stack_with_flags mm/kmsan/kmsan.c:279 [inline]
 kmsan_alloc_meta_for_pages+0x161/0x3a0 mm/kmsan/kmsan.c:815
 kmsan_alloc_page+0x82/0xe0 mm/kmsan/kmsan.c:885
 __alloc_pages_nodemask+0xf7b/0x5cc0 mm/page_alloc.c:4402
 alloc_pages_vma+0xcc6/0x17f0 mm/mempolicy.c:2057
 new_page+0x3a4/0x5e0 mm/mempolicy.c:1115
 unmap_and_move mm/migrate.c:1156 [inline]
 migrate_pages+0x6ab/0x4110 mm/migrate.c:1398
 do_mbind mm/mempolicy.c:1216 [inline]
 kernel_mbind+0x2090/0x21e0 mm/mempolicy.c:1333
 __do_sys_mbind mm/mempolicy.c:1340 [inline]
 __se_sys_mbind mm/mempolicy.c:1336 [inline]
 __x64_sys_mbind+0x1a1/0x200 mm/mempolicy.c:1336
 do_syscall_64+0x15b/0x230 arch/x86/entry/common.c:287
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Bytes 0-1376 of 1377 are uninitialized
Memory access starts at ffff88017f1a1000
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