From: Andrew Morton <akpm@linux-foundation.org>
To: liuqiangneo@163.com
Cc: jgg@ziepe.ca, leon@kernel.org, linux-mm@kvack.org,
linux-kernel@vger.kernel.org, Qiang Liu <liuqiang@kylinos.cn>
Subject: Re: [PATCH] lib/test_hmm: fix NULL deref and wrong direction in devmem fault debug message
Date: Tue, 11 Aug 2026 18:24:40 -0700 [thread overview]
Message-ID: <20260811182440.79cf147171dc7f87762a949d@linux-foundation.org> (raw)
In-Reply-To: <20260811092256.102101-1-liuqiangneo@163.com>
On Tue, 11 Aug 2026 17:22:55 +0800 liuqiangneo@163.com wrote:
> From: Qiang Liu <liuqiang@kylinos.cn>
>
> Move pr_debug() inside the `if (dpage)` block to avoid a NULL deref,
> and fix the direction label from "sys to dev" to "dev to sys" to match
> the device-to-system copy.
>
> ...
>
> --- a/lib/test_hmm.c
> +++ b/lib/test_hmm.c
> @@ -1151,10 +1151,9 @@ static vm_fault_t dmirror_devmem_fault_alloc_and_copy(struct migrate_vma *args,
> if (!dpage && !order)
> return VM_FAULT_OOM;
>
> - pr_debug("migrating from sys to dev pfn src: 0x%lx pfn dst: 0x%lx\n",
> - page_to_pfn(spage), page_to_pfn(dpage));
> -
> if (dpage) {
> + pr_debug("migrating from dev to sys pfn src: 0x%lx pfn dst: 0x%lx\n",
> + page_to_pfn(spage), page_to_pfn(dpage));
> lock_page(dpage);
> *dst |= migrate_pfn(page_to_pfn(dpage));
> }
Current kernel code doesn't look like this?
prev parent reply other threads:[~2026-08-12 1:24 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-08-11 9:22 liuqiangneo
2026-08-12 1:24 ` Andrew Morton [this message]
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