linux-kernel - Re: [mm/debug_vm_pgtable/locks] c50eb1ed65: BUG:sleeping_function_called_from_invalid_context_at_mm/page

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Date:   Sun, 13 Sep 2020 13:52:03 +0530
From:   "Aneesh Kumar K.V" <aneesh.kumar@...ux.ibm.com>
To:     kernel test robot <lkp@...el.com>
Cc:     Stephen Rothwell <sfr@...b.auug.org.au>,
        Anshuman Khandual <anshuman.khandual@....com>,
        Christophe Leroy <christophe.leroy@...roup.eu>,
        Michael Ellerman <mpe@...erman.id.au>,
        Andrew Morton <akpm@...ux-foundation.org>,
        LKML <linux-kernel@...r.kernel.org>, lkp@...ts.01.org,
        lkp@...el.com
Subject: Re: [mm/debug_vm_pgtable/locks] c50eb1ed65:
 BUG:sleeping_function_called_from_invalid_context_at_mm/page_alloc.c

kernel test robot <lkp@...el.com> writes:

> Greeting,
>
> FYI, we noticed the following commit (built with gcc-9):
>
> commit: c50eb1ed654b59efad96884cc26895a0acd7a15a ("mm/debug_vm_pgtable/locks: move non page table modifying test together")
> https://git.kernel.org/cgit/linux/kernel/git/next/linux-next.git master
>
>
> in testcase: boot
>
> on test machine: qemu-system-i386 -enable-kvm -cpu SandyBridge -smp 2 -m 8G
>
> caused below changes (please refer to attached dmesg/kmsg for entire log/backtrace):
>
>
> +----------------------------------------------------------------------+------------+------------+
> |                                                                      | 5c65ca35e5 | c50eb1ed65 |
> +----------------------------------------------------------------------+------------+------------+
> | boot_successes                                                       | 18         | 0          |
> | boot_failures                                                        | 0          | 10         |
> | BUG:sleeping_function_called_from_invalid_context_at_mm/page_alloc.c | 0          | 10         |
> +----------------------------------------------------------------------+------------+------------+
>
>
> If you fix the issue, kindly add following tag
> Reported-by: kernel test robot <lkp@...el.com>
>

How about this?

>From a654324a2d09c61b9fb271b550f543ef7b09adc1 Mon Sep 17 00:00:00 2001
From: "Aneesh Kumar K.V" <aneesh.kumar@...ux.ibm.com>
Date: Sun, 13 Sep 2020 13:34:26 +0530
Subject: [PATCH] mm/debug_vm_pgtable: Avoid doing memory allocation with
 pgtable_t mapped.

With highmem, pte_alloc_map() keep the level4 page table mapped using
kmap_atomic(). Avoid doing new memory allocation with page table
mapped like above.

[    9.409233] BUG: sleeping function called from invalid context at mm/page_alloc.c:4822
[    9.410557] in_atomic(): 1, irqs_disabled(): 0, non_block: 0, pid: 1, name: swapper
[    9.411932] no locks held by swapper/1.
[    9.412595] CPU: 0 PID: 1 Comm: swapper Not tainted 5.9.0-rc3-00323-gc50eb1ed654b5 #2
[    9.413824] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.12.0-1 04/01/2014
[    9.415207] Call Trace:
[    9.415651]  ? ___might_sleep.cold+0xa7/0xcc
[    9.416367]  ? __alloc_pages_nodemask+0x14c/0x5b0
[    9.417055]  ? swap_migration_tests+0x50/0x293
[    9.417704]  ? debug_vm_pgtable+0x4bc/0x708
[    9.418287]  ? swap_migration_tests+0x293/0x293
[    9.418911]  ? do_one_initcall+0x82/0x3cb
[    9.419465]  ? parse_args+0x1bd/0x280
[    9.419983]  ? rcu_read_lock_sched_held+0x36/0x60
[    9.420673]  ? trace_initcall_level+0x1f/0xf3
[    9.421279]  ? trace_initcall_level+0xbd/0xf3
[    9.421881]  ? do_basic_setup+0x9d/0xdd
[    9.422410]  ? do_basic_setup+0xc3/0xdd
[    9.422938]  ? kernel_init_freeable+0x72/0xa3
[    9.423539]  ? rest_init+0x134/0x134
[    9.424055]  ? kernel_init+0x5/0x12c
[    9.424574]  ? ret_from_fork+0x19/0x30

Reported-by: kernel test robot <lkp@...el.com>
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@...ux.ibm.com>
---
 mm/debug_vm_pgtable.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/mm/debug_vm_pgtable.c b/mm/debug_vm_pgtable.c
index d12bde82ae95..109fdf9953ad 100644
--- a/mm/debug_vm_pgtable.c
+++ b/mm/debug_vm_pgtable.c
@@ -994,7 +994,10 @@ static int __init debug_vm_pgtable(void)
 	p4dp = p4d_alloc(mm, pgdp, vaddr);
 	pudp = pud_alloc(mm, p4dp, vaddr);
 	pmdp = pmd_alloc(mm, pudp, vaddr);
-	ptep = pte_alloc_map(mm, pmdp, vaddr);
+	/*
+	 * Allocate pgtable_t
+	 */
+	pte_alloc(mm, pmdp);
 
 	/*
 	 * Save all the page table page addresses as the page table
@@ -1048,8 +1051,7 @@ static int __init debug_vm_pgtable(void)
 	 * proper page table lock.
 	 */
 
-	ptl = pte_lockptr(mm, pmdp);
-	spin_lock(ptl);
+	ptep = pte_offset_map_lock(mm, pmdp, vaddr, &ptl);
 	pte_clear_tests(mm, ptep, pte_aligned, vaddr, prot);
 	pte_advanced_tests(mm, vma, ptep, pte_aligned, vaddr, prot);
 	pte_unmap_unlock(ptep, ptl);
-- 
2.26.2