[syzbot] [mm?] KMSAN: uninit-value in zswap_store

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit:    614da38e2f7a Merge tag 'hid-for-linus-2024051401' of git:/..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=113f3fd6980000
kernel config:  https://syzkaller.appspot.com/x/.config?x=f5d2cbf33633f507
dashboard link: https://syzkaller.appspot.com/bug?extid=9c1fe13fcb51574b249b
compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/89eafb874b71/disk-614da38e.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/356000512ad9/vmlinux-614da38e.xz
kernel image: https://storage.googleapis.com/syzbot-assets/839c73939115/bzImage-614da38e.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+9c1fe13fcb51574b249b@xxxxxxxxxxxxxxxxxxxxxxxxx

=====================================================
BUG: KMSAN: uninit-value in zswap_is_page_same_filled mm/zswap.c:1481 [inline]
BUG: KMSAN: uninit-value in zswap_store+0x1008/0x2ca0 mm/zswap.c:1553
 zswap_is_page_same_filled mm/zswap.c:1481 [inline]
 zswap_store+0x1008/0x2ca0 mm/zswap.c:1553
 swap_writepage+0x126/0x4c0 mm/page_io.c:198
 shmem_writepage+0x1826/0x1f70 mm/shmem.c:1518
 pageout mm/vmscan.c:660 [inline]
 shrink_folio_list+0x4a55/0x7910 mm/vmscan.c:1323
 evict_folios+0x9d7f/0xcc20 mm/vmscan.c:4537
 try_to_shrink_lruvec+0x160e/0x1a50 mm/vmscan.c:4733
 shrink_one+0x66f/0xd40 mm/vmscan.c:4772
 shrink_many mm/vmscan.c:4835 [inline]
 lru_gen_shrink_node mm/vmscan.c:4935 [inline]
 shrink_node+0x4856/0x55f0 mm/vmscan.c:5894
 kswapd_shrink_node mm/vmscan.c:6704 [inline]
 balance_pgdat mm/vmscan.c:6895 [inline]
 kswapd+0x1eba/0x4460 mm/vmscan.c:7164
 kthread+0x3e2/0x540 kernel/kthread.c:389
 ret_from_fork+0x6d/0x90 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244

Uninit was stored to memory at:
 memcpy_from_iter lib/iov_iter.c:73 [inline]
 iterate_bvec include/linux/iov_iter.h:122 [inline]
 iterate_and_advance2 include/linux/iov_iter.h:249 [inline]
 iterate_and_advance include/linux/iov_iter.h:271 [inline]
 __copy_from_iter lib/iov_iter.c:249 [inline]
 copy_page_from_iter_atomic+0x12b7/0x2ae0 lib/iov_iter.c:481
 generic_perform_write+0x4c1/0xc60 mm/filemap.c:3982
 shmem_file_write_iter+0x2bd/0x2f0 mm/shmem.c:2920
 do_iter_readv_writev+0x7e6/0x960
 vfs_iter_write+0x459/0xd00 fs/read_write.c:895
 lo_write_bvec drivers/block/loop.c:246 [inline]
 lo_write_simple drivers/block/loop.c:267 [inline]
 do_req_filebacked drivers/block/loop.c:491 [inline]
 loop_handle_cmd drivers/block/loop.c:1907 [inline]
 loop_process_work+0x1502/0x3440 drivers/block/loop.c:1942
 loop_rootcg_workfn+0x2b/0x40 drivers/block/loop.c:1973
 process_one_work kernel/workqueue.c:3267 [inline]
 process_scheduled_works+0xa81/0x1bd0 kernel/workqueue.c:3348
 worker_thread+0xea5/0x1560 kernel/workqueue.c:3429
 kthread+0x3e2/0x540 kernel/kthread.c:389
 ret_from_fork+0x6d/0x90 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244

Uninit was created at:
 __alloc_pages+0x9d6/0xe70 mm/page_alloc.c:4598
 alloc_pages_mpol+0x299/0x990 mm/mempolicy.c:2264
 alloc_pages mm/mempolicy.c:2335 [inline]
 folio_alloc+0x1d0/0x230 mm/mempolicy.c:2342
 filemap_alloc_folio+0xa6/0x440 mm/filemap.c:984
 __filemap_get_folio+0xa10/0x14b0 mm/filemap.c:1926
 grow_dev_folio fs/buffer.c:1042 [inline]
 grow_buffers fs/buffer.c:1108 [inline]
 __getblk_slow fs/buffer.c:1134 [inline]
 bdev_getblk+0x39b/0xc80 fs/buffer.c:1429
 __getblk include/linux/buffer_head.h:355 [inline]
 sb_getblk include/linux/buffer_head.h:361 [inline]
 ext4_getblk+0x3da/0xe00 fs/ext4/inode.c:843
 ext4_xattr_inode_write fs/ext4/xattr.c:1421 [inline]
 ext4_xattr_inode_lookup_create fs/ext4/xattr.c:1596 [inline]
 ext4_xattr_set_entry+0x574d/0x6880 fs/ext4/xattr.c:1718
 ext4_xattr_block_set+0xb94/0x4fb0 fs/ext4/xattr.c:2037
 ext4_xattr_move_to_block fs/ext4/xattr.c:2654 [inline]
 ext4_xattr_make_inode_space fs/ext4/xattr.c:2729 [inline]
 ext4_expand_extra_isize_ea+0x20bd/0x3560 fs/ext4/xattr.c:2821
 __ext4_expand_extra_isize+0x5dc/0x680 fs/ext4/inode.c:5789
 ext4_try_to_expand_extra_isize fs/ext4/inode.c:5832 [inline]
 __ext4_mark_inode_dirty+0x70d/0xa10 fs/ext4/inode.c:5910
 ext4_delete_inline_entry+0x650/0x7d0 fs/ext4/inline.c:1753
 ext4_delete_entry+0x13f/0x7d0 fs/ext4/namei.c:2719
 __ext4_unlink+0x9b8/0x11b0 fs/ext4/namei.c:3273
 ext4_unlink+0x226/0x630 fs/ext4/namei.c:3321
 vfs_unlink+0x676/0xa30 fs/namei.c:4343
 do_unlinkat+0x823/0xe10 fs/namei.c:4407
 __do_sys_unlinkat fs/namei.c:4450 [inline]
 __se_sys_unlinkat fs/namei.c:4443 [inline]
 __x64_sys_unlinkat+0x17c/0x230 fs/namei.c:4443
 x64_sys_call+0x846/0x3b50 arch/x86/include/generated/asm/syscalls_64.h:264
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xcf/0x1e0 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

CPU: 1 PID: 88 Comm: kswapd1 Not tainted 6.9.0-syzkaller-02707-g614da38e2f7a #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/02/2024
=====================================================


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