KMSAN: uninit-value in xa_load

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 14525656 compiler.h: reinstate missing KMSAN_INIT
git tree: https://github.com/google/kmsan.git master
console output: https://syzkaller.appspot.com/x/log.txt?x=105d7320900000
kernel config: https://syzkaller.appspot.com/x/.config?x=c534a9fad6323722
dashboard link: https://syzkaller.appspot.com/bug?extid=086ab5ca9eafd2379aa6
compiler: clang version 10.0.0 (https://github.com/llvm/llvm-project/ c2443155a0fb245c8f17f2c1c72b6ea391e86e81)
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=1303736f100000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=12096087100000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+086ab5...@syzkaller.appspotmail.com

=====================================================
BUG: KMSAN: uninit-value in xas_start lib/xarray.c:190 [inline]
BUG: KMSAN: uninit-value in xas_load lib/xarray.c:233 [inline]
BUG: KMSAN: uninit-value in xa_load+0x83b/0x8a0 lib/xarray.c:1305
CPU: 0 PID: 8440 Comm: syz-executor560 Not tainted 5.8.0-rc5-syzkaller #0
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+0x1df/0x240 lib/dump_stack.c:118
kmsan_report+0xf7/0x1e0 mm/kmsan/kmsan_report.c:121
__msan_warning+0x58/0xa0 mm/kmsan/kmsan_instr.c:215
xas_start lib/xarray.c:190 [inline]
xas_load lib/xarray.c:233 [inline]
xa_load+0x83b/0x8a0 lib/xarray.c:1305
_ucma_find_context drivers/infiniband/core/ucma.c:139 [inline]
ucma_get_ctx+0x7f/0x310 drivers/infiniband/core/ucma.c:152
ucma_get_ctx_dev drivers/infiniband/core/ucma.c:175 [inline]
ucma_accept+0x259/0xc90 drivers/infiniband/core/ucma.c:1148
ucma_write+0x5c5/0x630 drivers/infiniband/core/ucma.c:1764
do_loop_readv_writev fs/read_write.c:737 [inline]
do_iter_write+0x710/0xdc0 fs/read_write.c:1020
vfs_writev fs/read_write.c:1091 [inline]
do_writev+0x42d/0x8f0 fs/read_write.c:1134
__do_sys_writev fs/read_write.c:1207 [inline]
__se_sys_writev+0x9b/0xb0 fs/read_write.c:1204
__x64_sys_writev+0x4a/0x70 fs/read_write.c:1204
do_syscall_64+0xb0/0x150 arch/x86/entry/common.c:386
entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x4402e9
Code: Bad RIP value.
RSP: 002b:00007fffa058a4f8 EFLAGS: 00000246 ORIG_RAX: 0000000000000014
RAX: ffffffffffffffda RBX: 00000000004002c8 RCX: 00000000004402e9
RDX: 0000000000000001 RSI: 00000000200000c0 RDI: 0000000000000003
RBP: 00000000006ca018 R08: 0000000000000000 R09: 00000000004002c8
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000401af0
R13: 0000000000401b80 R14: 0000000000000000 R15: 0000000000000000

Local variable ----cmd@ucma_accept created at:
ucma_accept+0x95/0xc90 drivers/infiniband/core/ucma.c:1137
ucma_accept+0x95/0xc90 drivers/infiniband/core/ucma.c:1137
=====================================================


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