From: Harry Yoo <harry.yoo@oracle.com>
To: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Andrey Ryabinin <ryabinin.a.a@gmail.com>,
Daniel Axtens <dja@axtens.net>,
linux-kernel@vger.kernel.org, linux-mm@kvack.org,
kasan-dev@googlegroups.com, linux-s390@vger.kernel.org,
stable@vger.kernel.org
Subject: Re: [PATCH v9 1/1] kasan: Avoid sleepable page allocation from atomic context
Date: Sat, 17 May 2025 20:18:55 +0900 [thread overview]
Message-ID: <aChwn4mmYMdMSuEt@harry> (raw)
In-Reply-To: <c61d3560297c93ed044f0b1af085610353a06a58.1747316918.git.agordeev@linux.ibm.com>
On Thu, May 15, 2025 at 03:55:38PM +0200, Alexander Gordeev wrote:
> apply_to_pte_range() enters the lazy MMU mode and then invokes
> kasan_populate_vmalloc_pte() callback on each page table walk
> iteration. However, the callback can go into sleep when trying
> to allocate a single page, e.g. if an architecutre disables
> preemption on lazy MMU mode enter.
>
> On s390 if make arch_enter_lazy_mmu_mode() -> preempt_enable()
> and arch_leave_lazy_mmu_mode() -> preempt_disable(), such crash
> occurs:
>
> [ 0.663336] BUG: sleeping function called from invalid context at ./include/linux/sched/mm.h:321
> [ 0.663348] in_atomic(): 1, irqs_disabled(): 0, non_block: 0, pid: 2, name: kthreadd
> [ 0.663358] preempt_count: 1, expected: 0
> [ 0.663366] RCU nest depth: 0, expected: 0
> [ 0.663375] no locks held by kthreadd/2.
> [ 0.663383] Preemption disabled at:
> [ 0.663386] [<0002f3284cbb4eda>] apply_to_pte_range+0xfa/0x4a0
> [ 0.663405] CPU: 0 UID: 0 PID: 2 Comm: kthreadd Not tainted 6.15.0-rc5-gcc-kasan-00043-gd76bb1ebb558-dirty #162 PREEMPT
> [ 0.663408] Hardware name: IBM 3931 A01 701 (KVM/Linux)
> [ 0.663409] Call Trace:
> [ 0.663410] [<0002f3284c385f58>] dump_stack_lvl+0xe8/0x140
> [ 0.663413] [<0002f3284c507b9e>] __might_resched+0x66e/0x700
> [ 0.663415] [<0002f3284cc4f6c0>] __alloc_frozen_pages_noprof+0x370/0x4b0
> [ 0.663419] [<0002f3284ccc73c0>] alloc_pages_mpol+0x1a0/0x4a0
> [ 0.663421] [<0002f3284ccc8518>] alloc_frozen_pages_noprof+0x88/0xc0
> [ 0.663424] [<0002f3284ccc8572>] alloc_pages_noprof+0x22/0x120
> [ 0.663427] [<0002f3284cc341ac>] get_free_pages_noprof+0x2c/0xc0
> [ 0.663429] [<0002f3284cceba70>] kasan_populate_vmalloc_pte+0x50/0x120
> [ 0.663433] [<0002f3284cbb4ef8>] apply_to_pte_range+0x118/0x4a0
> [ 0.663435] [<0002f3284cbc7c14>] apply_to_pmd_range+0x194/0x3e0
> [ 0.663437] [<0002f3284cbc99be>] __apply_to_page_range+0x2fe/0x7a0
> [ 0.663440] [<0002f3284cbc9e88>] apply_to_page_range+0x28/0x40
> [ 0.663442] [<0002f3284ccebf12>] kasan_populate_vmalloc+0x82/0xa0
> [ 0.663445] [<0002f3284cc1578c>] alloc_vmap_area+0x34c/0xc10
> [ 0.663448] [<0002f3284cc1c2a6>] __get_vm_area_node+0x186/0x2a0
> [ 0.663451] [<0002f3284cc1e696>] __vmalloc_node_range_noprof+0x116/0x310
> [ 0.663454] [<0002f3284cc1d950>] __vmalloc_node_noprof+0xd0/0x110
> [ 0.663457] [<0002f3284c454b88>] alloc_thread_stack_node+0xf8/0x330
> [ 0.663460] [<0002f3284c458d56>] dup_task_struct+0x66/0x4d0
> [ 0.663463] [<0002f3284c45be90>] copy_process+0x280/0x4b90
> [ 0.663465] [<0002f3284c460940>] kernel_clone+0xd0/0x4b0
> [ 0.663467] [<0002f3284c46115e>] kernel_thread+0xbe/0xe0
> [ 0.663469] [<0002f3284c4e440e>] kthreadd+0x50e/0x7f0
> [ 0.663472] [<0002f3284c38c04a>] __ret_from_fork+0x8a/0xf0
> [ 0.663475] [<0002f3284ed57ff2>] ret_from_fork+0xa/0x38
>
> Instead of allocating single pages per-PTE, bulk-allocate the
> shadow memory prior to applying kasan_populate_vmalloc_pte()
> callback on a page range.
>
> Suggested-by: Andrey Ryabinin <ryabinin.a.a@gmail.com>
> Cc: stable@vger.kernel.org
> Fixes: 3c5c3cfb9ef4 ("kasan: support backing vmalloc space with real shadow memory")
> Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
> ---
V9 of this patch looks good to me,
Reviewed-by: Harry Yoo <harry.yoo@oracle.com>
--
Cheers,
Harry / Hyeonggon
prev parent reply other threads:[~2025-05-17 11:19 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-05-15 13:55 [PATCH v9 0/1] kasan: Avoid sleepable page allocation from atomic context Alexander Gordeev
2025-05-15 13:55 ` [PATCH v9 1/1] " Alexander Gordeev
2025-05-17 11:18 ` Harry Yoo [this message]
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