* [PATCH] lib/test_hmm: fix NULL deref and wrong direction in devmem fault debug message
@ 2026-08-11 9:22 liuqiangneo
2026-08-12 1:24 ` Andrew Morton
0 siblings, 1 reply; 2+ messages in thread
From: liuqiangneo @ 2026-08-11 9:22 UTC (permalink / raw)
To: jgg, leon, akpm; +Cc: linux-mm, linux-kernel, Qiang Liu
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.
Assisted-by: Qoder:Qwen-3.8-MAX-Preview
Signed-off-by: Qiang Liu <liuqiang@kylinos.cn>
---
lib/test_hmm.c | 5 ++---
1 file changed, 2 insertions(+), 3 deletions(-)
diff --git a/lib/test_hmm.c b/lib/test_hmm.c
index 6e72a0d8a53d..1dae93ab1e93 100644
--- 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));
}
--
2.43.0
No virus found
Checked by Hillstone Network AntiVirus
^ permalink raw reply [flat|nested] 2+ messages in thread* Re: [PATCH] lib/test_hmm: fix NULL deref and wrong direction in devmem fault debug message
2026-08-11 9:22 [PATCH] lib/test_hmm: fix NULL deref and wrong direction in devmem fault debug message liuqiangneo
@ 2026-08-12 1:24 ` Andrew Morton
0 siblings, 0 replies; 2+ messages in thread
From: Andrew Morton @ 2026-08-12 1:24 UTC (permalink / raw)
To: liuqiangneo; +Cc: jgg, leon, linux-mm, linux-kernel, Qiang Liu
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?
^ permalink raw reply [flat|nested] 2+ messages in thread
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2026-08-11 9:22 [PATCH] lib/test_hmm: fix NULL deref and wrong direction in devmem fault debug message liuqiangneo
2026-08-12 1:24 ` Andrew Morton
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