Subject: Re: [syzbot] [bridge?] kernel BUG in __get_vm_area_node

From: Uladzislau Rezki <[email-masked]>
Date: Tue, 12 May 2026 11:26:06 +0200

On Tue, May 12, 2026 at 11:47:54AM +0300, Ido Schimmel wrote:
> On Sat, May 09, 2026 at 12:35:24PM -0700, syzbot wrote:
> > Hello,
> > 
> > syzbot found the following issue on:
> > 
> > HEAD commit:    9207d47f966b Merge tag 'for-linus' of git://git.kernel.org..
> > git tree:       upstream
> > console output: https://syzkaller.appspot.com/x/log.txt?x=17e44d06580000
> > kernel config:  https://syzkaller.appspot.com/x/.config?x=d0f0911eedbc130a
> > dashboard link: https://syzkaller.appspot.com/bug?extid=8b12fc6e0fb139765b58
> > compiler:       gcc (Debian 14.2.0-19) 14.2.0, GNU ld (GNU Binutils for Debian) 2.44
> > userspace arch: i386
> > 
> > Unfortunately, I don't have any reproducer for this issue yet.
> > 
> > Downloadable assets:
> > disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/d900f083ada3/non_bootable_disk-9207d47f.raw.xz
> > vmlinux: https://storage.googleapis.com/syzbot-assets/6c5e883f31aa/vmlinux-9207d47f.xz
> > kernel image: https://storage.googleapis.com/syzbot-assets/19f3e863ae5c/bzImage-9207d47f.xz
> > 
> > IMPORTANT: if you fix the issue, please add the following tag to the commit:
> > Reported-by: [email-masked]
> > 
> > ------------[ cut here ]------------
> > kernel BUG at mm/vmalloc.c:3206!
> 
> It seems that this bug was fixed by commit 30c19366636f ("mm: fix BUG
> splat with kvmalloc + GFP_ATOMIC"), but then commit c6307674ed82 ("mm:
> kvmalloc: add non-blocking support for vmalloc") re-introduced it.
> 
> Uladzislau, can you please look into it?
> 
> Note that the bridge is calling rhashtable_lookup_insert_fast() with BH
> disabled.
> 
Yep, since vmalloc can be called with ATOMIC/NOWAIT flags now. I am
checking this. Probably we can just remove below check:

<snip>
diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index 676851d5cfe7..3d338e4bcbf7 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -3209,7 +3209,6 @@ struct vm_struct *__get_vm_area_node(unsigned long size,
        struct vm_struct *area;
        unsigned long requested_size = size;

-       BUG_ON(in_interrupt());
        size = ALIGN(size, 1ul << shift);
        if (unlikely(!size))
                return NULL;
<snip>

We have already the check:

	gfp_mask = gfp_mask & GFP_RECLAIM_MASK;
	allow_block = gfpflags_allow_blocking(gfp_mask);
	might_sleep_if(allow_block);

in alloc_vmap_area().

--
Uladzislau Rezki