linux-kernel - [syzbot] [mm?] KMSAN: uninit-value in __alloc_frozen_pages

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Message-ID: <67b8a9a8.050a0220.14d86d.0579.GAE@google.com>
Date: Fri, 21 Feb 2025 08:28:24 -0800
From: syzbot <syzbot+0cfd5e38e96a5596f2b6@...kaller.appspotmail.com>
To: akpm@...ux-foundation.org, linux-kernel@...r.kernel.org, 
	linux-mm@...ck.org, syzkaller-bugs@...glegroups.com
Subject: [syzbot] [mm?] KMSAN: uninit-value in __alloc_frozen_pages_noprof

Hello,

syzbot found the following issue on:

HEAD commit:    27eddbf34490 Merge tag 'net-6.14-rc4' of git://git.kernel...
git tree:       upstream
console+strace: https://syzkaller.appspot.com/x/log.txt?x=133a6ba4580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=8cf1217edc1cc7da
dashboard link: https://syzkaller.appspot.com/bug?extid=0cfd5e38e96a5596f2b6
compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=12dff5b0580000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=179fbba4580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/31d2c5efefde/disk-27eddbf3.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/18b5dc7f96c2/vmlinux-27eddbf3.xz
kernel image: https://storage.googleapis.com/syzbot-assets/f6a957d3f940/bzImage-27eddbf3.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+0cfd5e38e96a5596f2b6@...kaller.appspotmail.com

=====================================================
BUG: KMSAN: uninit-value in __alloc_pages_slowpath+0xee8/0x16c0 mm/page_alloc.c:4416
 __alloc_pages_slowpath+0xee8/0x16c0 mm/page_alloc.c:4416
 __alloc_frozen_pages_noprof+0xa4c/0xe00 mm/page_alloc.c:4752
 alloc_pages_mpol+0x4cd/0x890 mm/mempolicy.c:2270
 alloc_frozen_pages_noprof mm/mempolicy.c:2341 [inline]
 alloc_pages_noprof mm/mempolicy.c:2361 [inline]
 folio_alloc_noprof+0x1dc/0x350 mm/mempolicy.c:2371
 filemap_alloc_folio_noprof+0xa6/0x440 mm/filemap.c:1019
 __filemap_get_folio+0xb9a/0x1840 mm/filemap.c:1970
 grow_dev_folio fs/buffer.c:1039 [inline]
 grow_buffers fs/buffer.c:1105 [inline]
 __getblk_slow fs/buffer.c:1131 [inline]
 bdev_getblk+0x2c9/0xab0 fs/buffer.c:1431
 getblk_unmovable include/linux/buffer_head.h:369 [inline]
 ext4_getblk+0x3b7/0xe50 fs/ext4/inode.c:864
 ext4_bread_batch+0x9f/0x7d0 fs/ext4/inode.c:933
 __ext4_find_entry+0x1ebb/0x36c0 fs/ext4/namei.c:1627
 ext4_lookup_entry fs/ext4/namei.c:1729 [inline]
 ext4_lookup+0x189/0xb40 fs/ext4/namei.c:1797
 __lookup_slow+0x538/0x710 fs/namei.c:1793
 lookup_slow+0x6a/0xd0 fs/namei.c:1810
 walk_component fs/namei.c:2114 [inline]
 link_path_walk+0xf29/0x1420 fs/namei.c:2479
 path_openat+0x30f/0x6250 fs/namei.c:3985
 do_filp_open+0x268/0x600 fs/namei.c:4016
 do_sys_openat2+0x1bf/0x2f0 fs/open.c:1428
 do_sys_open fs/open.c:1443 [inline]
 __do_sys_openat fs/open.c:1459 [inline]
 __se_sys_openat fs/open.c:1454 [inline]
 __x64_sys_openat+0x2a1/0x310 fs/open.c:1454
 x64_sys_call+0x36f5/0x3c30 arch/x86/include/generated/asm/syscalls_64.h:258
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xcd/0x1e0 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Local variable compact_result created at:
 __alloc_pages_slowpath+0x66/0x16c0 mm/page_alloc.c:4218
 __alloc_frozen_pages_noprof+0xa4c/0xe00 mm/page_alloc.c:4752

CPU: 0 UID: 0 PID: 5126 Comm: syslogd Not tainted 6.14.0-rc3-syzkaller-00137-g27eddbf34490 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 12/27/2024
=====================================================


---
This report is generated by a bot. It may contain errors.
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