linux-kernel - Re: [PATCH v2 04/16] mm: Change do_vmi_align

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Message-ID: <20230620130412.lxri53iekoq6lpfb@revolver>
Date:   Tue, 20 Jun 2023 09:04:12 -0400
From:   "Liam R. Howlett" <Liam.Howlett@...cle.com>
To:     Sergey Senozhatsky <senozhatsky@...omium.org>
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        maple-tree@...ts.infradead.org, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org,
        Peng Zhang <zhangpeng.00@...edance.com>
Subject: Re: [PATCH v2 04/16] mm: Change do_vmi_align_munmap() side tree index

* Sergey Senozhatsky <senozhatsky@...omium.org> [230620 08:26]:
> Hello Liam,
> 
> On (23/06/12 16:39), Liam R. Howlett wrote:
> [..]
> > @@ -2450,17 +2452,17 @@ do_vmi_align_munmap(struct vma_iterator *vmi, struct vm_area_struct *vma,
> >  #if defined(CONFIG_DEBUG_VM_MAPLE_TREE)
> >  	/* Make sure no VMAs are about to be lost. */
> >  	{
> > -		MA_STATE(test, &mt_detach, start, end - 1);
> > +		MA_STATE(test, &mt_detach, 0, 0);
> >  		struct vm_area_struct *vma_mas, *vma_test;
> >  		int test_count = 0;
> >  
> >  		vma_iter_set(vmi, start);
> >  		rcu_read_lock();
> > -		vma_test = mas_find(&test, end - 1);
> > +		vma_test = mas_find(&test, count - 1);
> >  		for_each_vma_range(*vmi, vma_mas, end) {
> >  			BUG_ON(vma_mas != vma_test);
> >  			test_count++;
> > -			vma_test = mas_next(&test, end - 1);
> > +			vma_test = mas_next(&test, count - 1);
> >  		}
> >  		rcu_read_unlock();
> >  		BUG_ON(count != test_count);
> 
> Something isn't quite working, I'm hitting BUG_ON(vma_mas != vma_test)

Is this with next by any chance?  There's a merge conflict which I'll
have to fix, but I won't be getting to it in time so the patches will
not make this merge window.

> 
> [    8.156437] ------------[ cut here ]------------
> [    8.160473] kernel BUG at mm/mmap.c:2439!
> [    8.163894] invalid opcode: 0000 [#1] PREEMPT SMP PTI
> 
> RIP: 0010:do_vmi_align_munmap+0x489/0x8a0
> 
> [    8.207867] Call Trace:
> [    8.208463]  <TASK>
> [    8.209018]  ? die+0x32/0x80
> [    8.209709]  ? do_trap+0xd2/0x100
> [    8.210520]  ? do_vmi_align_munmap+0x489/0x8a0
> [    8.211576]  ? do_vmi_align_munmap+0x489/0x8a0
> [    8.212639]  ? do_error_trap+0x94/0x110
> [    8.213549]  ? do_vmi_align_munmap+0x489/0x8a0
> [    8.214581]  ? exc_invalid_op+0x49/0x60
> [    8.215494]  ? do_vmi_align_munmap+0x489/0x8a0
> [    8.216576]  ? asm_exc_invalid_op+0x16/0x20
> [    8.217562]  ? do_vmi_align_munmap+0x489/0x8a0
> [    8.218626]  do_vmi_munmap+0xc7/0x120
> [    8.219494]  __vm_munmap+0xaa/0x1c0
> [    8.220370]  __x64_sys_munmap+0x17/0x20
> [    8.221275]  do_syscall_64+0x34/0x80
> [    8.222165]  entry_SYSCALL_64_after_hwframe+0x63/0xcd
> [    8.223359] RIP: 0033:0x7fdb0e2fca97
> [    8.224224] Code: ff ff ff ff c3 66 0f 1f 44 00 00 f7 d8 89 05 20 28 01 00 48 c7 c0 ff ff ff ff c3 0f 1f 84 00 00 00 00 00 b8 0b 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8d 0d f9 27 01 00 f7 d8 89 01 48 83
> [    8.228432] RSP: 002b:00007ffd15458348 EFLAGS: 00000202 ORIG_RAX: 000000000000000b
> [    8.230175] RAX: ffffffffffffffda RBX: 0000562081a347b0 RCX: 00007fdb0e2fca97
> [    8.231833] RDX: 0000000000000002 RSI: 0000000000004010 RDI: 00007fdb0e2d5000
> [    8.233513] RBP: 00007ffd154584d0 R08: 0000000000000000 R09: 0000562081a3fd30
> [    8.235178] R10: 0000562081a3fd18 R11: 0000000000000202 R12: 00007ffd15458388
> [    8.236861] R13: 00007ffd15458438 R14: 00007ffd15458370 R15: 0000562081a347b0