Re: [syzbot] [mm?] WARNING in __folio_rmap_sanity_checks

[Yin, Fengwei]

On 1/3/2024 8:13 PM, David Hildenbrand wrote:
> On 03.01.24 12:48, syzbot wrote:
> > Hello,
> >
> > syzbot found the following issue on:
> >
> > HEAD commit:    ab0b3e6ef50d Add linux-next specific files for 20240102
> > git tree:       linux-next
> > console+strace: https://syzkaller.appspot.com/x/log.txt?x=17be3e09e80000
> > kernel config:  
> > https://syzkaller.appspot.com/x/.config?x=a14a6350374945f9
> > dashboard link: 
> > https://syzkaller.appspot.com/bug?extid=50ef73537bbc393a25bb
> > compiler:       gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils 
> > for Debian) 2.40
> > syz repro:      
> > https://syzkaller.appspot.com/x/repro.syz?x=14e2256ee80000
> > C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=17b57db5e80000
> >
> > Downloadable assets:
> > disk image: 
> > https://storage.googleapis.com/syzbot-assets/4e6376fe5764/disk-ab0b3e6e.raw.xz
> > vmlinux: 
> > https://storage.googleapis.com/syzbot-assets/7cb9ecbaf001/vmlinux-ab0b3e6e.xz
> > kernel image: 
> > https://storage.googleapis.com/syzbot-assets/2c1a9a6d424f/bzImage-ab0b3e6e.xz
> >
> > The issue was bisected to:
> >
> > commit 68f0320824fa59c5429cbc811e6c46e7a30ea32c
> > Author: David Hildenbrand <david@xxxxxxxxxx>
> > Date:   Wed Dec 20 22:44:31 2023 +0000
> >
> >      mm/rmap: convert folio_add_file_rmap_range() into 
> > folio_add_file_rmap_[pte|ptes|pmd]()
> >
> > bisection log:  
> > https://syzkaller.appspot.com/x/bisect.txt?x=10b9e1b1e80000
> > final oops:     
> > https://syzkaller.appspot.com/x/report.txt?x=12b9e1b1e80000
> > console output: https://syzkaller.appspot.com/x/log.txt?x=14b9e1b1e80000
> >
> > IMPORTANT: if you fix the issue, please add the following tag to the 
> > commit:
> > Reported-by: syzbot+50ef73537bbc393a25bb@xxxxxxxxxxxxxxxxxxxxxxxxx
> > Fixes: 68f0320824fa ("mm/rmap: convert folio_add_file_rmap_range() 
> > into folio_add_file_rmap_[pte|ptes|pmd]()")
> >
> >   kasan_quarantine_reduce+0x18e/0x1d0 mm/kasan/quarantine.c:283
> >   __kasan_slab_alloc+0x65/0x90 mm/kasan/common.c:324
> >   kasan_slab_alloc include/linux/kasan.h:201 [inline]
> >   slab_post_alloc_hook mm/slub.c:3813 [inline]
> >   slab_alloc_node mm/slub.c:3860 [inline]
> >   kmem_cache_alloc+0x136/0x320 mm/slub.c:3867
> >   vm_area_alloc+0x1f/0x220 kernel/fork.c:465
> >   mmap_region+0x3ae/0x2a90 mm/mmap.c:2804
> >   do_mmap+0x890/0xef0 mm/mmap.c:1379
> >   vm_mmap_pgoff+0x1a7/0x3c0 mm/util.c:573
> >   ksys_mmap_pgoff+0x421/0x5a0 mm/mmap.c:1425
> >   __do_sys_mmap arch/x86/kernel/sys_x86_64.c:93 [inline]
> >   __se_sys_mmap arch/x86/kernel/sys_x86_64.c:86 [inline]
> >   __x64_sys_mmap+0x125/0x190 arch/x86/kernel/sys_x86_64.c:86
> >   do_syscall_x64 arch/x86/entry/common.c:52 [inline]
> >   do_syscall_64+0xd0/0x250 arch/x86/entry/common.c:83
> >   entry_SYSCALL_64_after_hwframe+0x62/0x6a
> > ------------[ cut here ]------------
> > WARNING: CPU: 1 PID: 5059 at include/linux/rmap.h:202 
> > __folio_rmap_sanity_checks+0x4d5/0x630 include/linux/rmap.h:202
> > Modules linked in:
> > CPU: 1 PID: 5059 Comm: syz-executor115 Not tainted 
> > 6.7.0-rc8-next-20240102-syzkaller #0
> > Hardware name: Google Google Compute Engine/Google Compute Engine, 
> > BIOS Google 11/17/2023
> > RIP: 0010:__folio_rmap_sanity_checks+0x4d5/0x630 include/linux/rmap.h:202
> > Code: 41 83 e4 01 44 89 e6 e8 79 bc b7 ff 45 84 e4 0f 85 08 fc ff ff 
> > e8 3b c1 b7 ff 48 c7 c6 e0 b5 d9 8a 48 89 df e8 5c 12 f7 ff 90 <0f> 0b 
> > 90 e9 eb fb ff ff e8 1e c1 b7 ff be 01 00 00 00 48 89 df e8
> > RSP: 0018:ffffc900038df978 EFLAGS: 00010293
> > RAX: 0000000000000000 RBX: ffffea00008cde00 RCX: ffffffff81687419
> > RDX: ffff88807becbb80 RSI: ffffffff81d06104 RDI: 0000000000000000
> > RBP: ffffea00008cde00 R08: 0000000000000000 R09: fffffbfff1e75f6a
> > R10: ffffffff8f3afb57 R11: 0000000000000001 R12: 0000000000000000
> > R13: 0000000000000001 R14: 0000000000000000 R15: dffffc0000000000
> > FS:  0000555556508380(0000) GS:ffff8880b9900000(0000) 
> > knlGS:0000000000000000
> > CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> > CR2: 00000000200000c0 CR3: 0000000079000000 CR4: 00000000003506f0
> > DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> > DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> > Call Trace:
> >   <TASK>
> >   __folio_add_rmap mm/rmap.c:1167 [inline]
> >   __folio_add_file_rmap mm/rmap.c:1452 [inline]
> >   folio_add_file_rmap_ptes+0x8e/0x2c0 mm/rmap.c:1478
> >   insert_page_into_pte_locked.isra.0+0x34d/0x960 mm/memory.c:1874
> >   insert_page mm/memory.c:1900 [inline]
> >   vm_insert_page+0x62c/0x8c0 mm/memory.c:2053
> >   packet_mmap+0x314/0x570 net/packet/af_packet.c:4594
> >   call_mmap include/linux/fs.h:2090 [inline]
> >   mmap_region+0x745/0x2a90 mm/mmap.c:2819
> >   do_mmap+0x890/0xef0 mm/mmap.c:1379
> >   vm_mmap_pgoff+0x1a7/0x3c0 mm/util.c:573
> >   ksys_mmap_pgoff+0x421/0x5a0 mm/mmap.c:1425
> >   __do_sys_mmap arch/x86/kernel/sys_x86_64.c:93 [inline]
> >   __se_sys_mmap arch/x86/kernel/sys_x86_64.c:86 [inline]
> >   __x64_sys_mmap+0x125/0x190 arch/x86/kernel/sys_x86_64.c:86
> >   do_syscall_x64 arch/x86/entry/common.c:52 [inline]
> >   do_syscall_64+0xd0/0x250 arch/x86/entry/common.c:83
> >   entry_SYSCALL_64_after_hwframe+0x62/0x6a
>
> If I am not wrong, that triggers:
>
> VM_WARN_ON_FOLIO(folio_test_large(folio) &&
>           !folio_test_large_rmappable(folio), folio);
>
> So we are trying to rmap a large folio that did not go through 
> folio_prep_large_rmappable().
>
> net/packet/af_packet.c calls vm_insert_page() on some pages/folios stoed 
> in the "struct packet_ring_buffer". No idea where that comes from, but I 
> suspect it's simply some compound allocation.
Looks like:
 alloc_pg_vec
   alloc_one_pg_vec_page
        gfp_t gfp_flags = GFP_KERNEL | __GFP_COMP |
                          __GFP_ZERO | __GFP_NOWARN | __GFP_NORETRY;

        buffer = (char *) __get_free_pages(gfp_flags, order);
So you are right here... :).


Regards
Yin, Fengwei

> Likely, rmap handling is completely bogus for these folios?