linux-kernel - Re: [syzbot] [mm?] WARNING in __folio_rmap_sanity

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Message-Id: <20240105090432.041a6f40b4402f0ee00ecc57@linux-foundation.org>
Date: Fri, 5 Jan 2024 09:04:32 -0800
From: Andrew Morton <akpm@...ux-foundation.org>
To: "Yin, Fengwei" <fengwei.yin@...el.com>
Cc: David Hildenbrand <david@...hat.com>, syzbot
 <syzbot+50ef73537bbc393a25bb@...kaller.appspotmail.com>,
 <linux-kernel@...r.kernel.org>, <linux-mm@...ck.org>,
 <ryan.roberts@....com>, <syzkaller-bugs@...glegroups.com>, Matthew Wilcox
 <willy@...radead.org>, netdev@...r.kernel.org
Subject: Re: [syzbot] [mm?] WARNING in __folio_rmap_sanity_checks

(cc netdev)

On Wed, 3 Jan 2024 22:16:13 +0800 "Yin, Fengwei" <fengwei.yin@...el.com> wrote:

> 
> 
> 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@...hat.com>
> >> 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@...kaller.appspotmail.com
> >> 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... :).

Can we suggest what af_packet should be doing to avoid this?