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* [PATCH v3] lib/test_bpf: Call page_address() on page acquired with GFP_KERNEL flag
@ 2023-06-22  7:52 Sumitra Sharma
  2023-06-26 20:36 ` Ira Weiny
  0 siblings, 1 reply; 4+ messages in thread
From: Sumitra Sharma @ 2023-06-22  7:52 UTC (permalink / raw)
  To: Alexei Starovoitov, Daniel Borkmann, Andrii Nakryiko,
	Martin KaFai Lau, Song Liu, Yonghong Song, John Fastabend,
	KP Singh, Stanislav Fomichev, Hao Luo, Jiri Olsa, bpf,
	linux-kernel
  Cc: Ira Weiny, Fabio, Deepak R Varma, Sumitra Sharma

generate_test_data() acquires a page with alloc_page(GFP_KERNEL).
The GFP_KERNEL is typical for kernel-internal allocations.
The caller requires ZONE_NORMAL or a lower zone for direct access.

Therefore the page cannot come from ZONE_HIGHMEM. Thus there's
no need to map it with kmap().

Also, the kmap() is being deprecated in favor of
kmap_local_page() [1].

Hence, use a plain page_address() directly.

Since the page passed to the page_address() is not from the highmem
zone, the page_address() function will always return a valid kernel
virtual address and will not return NULL. Hence, remove the check
'if (!ptr)'.

Remove the unused variable 'ptr'.

[1]: https://lore.kernel.org/all/20220813220034.806698-1-ira.weiny
@intel.com/

Suggested-by: Fabio M. De Francesco <fmdefrancesco@gmail.com>
Signed-off-by: Sumitra Sharma <sumitraartsy@gmail.com>
---

- Link to v1: https://lore.kernel.org/bpf/20230613073020.GA359792@sumitra.com/T/
- Link to v2: https://lore.kernel.org/lkml/3564297.R56niFO833@suse/T/

Changes in v3:
Noted by: Fabio M. De Francesco<fmdefrancesco@gmail.com>
	- Remove the check 'if (!ptr)'.
	- Remove the unused variable 'ptr'.
	- Change the commit message.

Changes in v2:
Noted by: Fabio M. De Francesco<fmdefrancesco@gmail.com>
	- Remove the kmap() call and call page_address() instead.
	- Change the commit subject and message.


 lib/test_bpf.c | 8 +-------
 1 file changed, 1 insertion(+), 7 deletions(-)

diff --git a/lib/test_bpf.c b/lib/test_bpf.c
index ade9ac672adb..448bc1b0b8b5 100644
--- a/lib/test_bpf.c
+++ b/lib/test_bpf.c
@@ -14381,18 +14381,12 @@ static void *generate_test_data(struct bpf_test *test, int sub)
 		 * single fragment to the skb, filled with
 		 * test->frag_data.
 		 */
-		void *ptr;
-
 		page = alloc_page(GFP_KERNEL);
 
 		if (!page)
 			goto err_kfree_skb;
 
-		ptr = kmap(page);
-		if (!ptr)
-			goto err_free_page;
-		memcpy(ptr, test->frag_data, MAX_DATA);
-		kunmap(page);
+		memcpy(page_address(page), test->frag_data, MAX_DATA);
 		skb_add_rx_frag(skb, 0, page, 0, MAX_DATA, MAX_DATA);
 	}
 
-- 
2.25.1


^ permalink raw reply related	[flat|nested] 4+ messages in thread
* [PATCH v3] lib/test_bpf: Call page_address() on page acquired with GFP_KERNEL flag
@ 2023-06-22  8:07 Sumitra Sharma
  2023-06-22 22:00 ` kernel test robot
  0 siblings, 1 reply; 4+ messages in thread
From: Sumitra Sharma @ 2023-06-22  8:07 UTC (permalink / raw)
  To: Alexei Starovoitov, Daniel Borkmann, Andrii Nakryiko,
	Martin KaFai Lau, Song Liu, Yonghong Song, John Fastabend,
	KP Singh, Stanislav Fomichev, Hao Luo, Jiri Olsa, bpf,
	linux-kernel
  Cc: Ira Weiny, Fabio, Deepak R Varma, Sumitra Sharma

generate_test_data() acquires a page with alloc_page(GFP_KERNEL).
The GFP_KERNEL is typical for kernel-internal allocations.
The caller requires ZONE_NORMAL or a lower zone for direct access.

Therefore the page cannot come from ZONE_HIGHMEM. Thus there's
no need to map it with kmap().

Also, the kmap() is being deprecated in favor of
kmap_local_page() [1].

Hence, use a plain page_address() directly.

Since the page passed to the page_address() is not from the highmem
zone, the page_address() function will always return a valid kernel
virtual address and will not return NULL. Hence, remove the check
'if (!ptr)'.

Remove the unused variable 'ptr'.

[1]: https://lore.kernel.org/all/20220813220034.806698-1-ira.weiny@intel.com/

Suggested-by: Fabio M. De Francesco <fmdefrancesco@gmail.com>
Signed-off-by: Sumitra Sharma <sumitraartsy@gmail.com>
---

- Link to v1: https://lore.kernel.org/bpf/20230613073020.GA359792@sumitra.com/T/
- Link to v2: https://lore.kernel.org/lkml/3564297.R56niFO833@suse/T/

Changes in v3:
Noted by: Fabio M. De Francesco<fmdefrancesco@gmail.com>
	- Remove the check 'if (!ptr)'.
	- Remove the unused variable 'ptr'.
	- Change the commit message.

Changes in v2:
Noted by: Fabio M. De Francesco<fmdefrancesco@gmail.com>
    - Remove the kmap() call and call page_address() instead.
    - Change the commit subject and message.


 lib/test_bpf.c | 8 +-------
 1 file changed, 1 insertion(+), 7 deletions(-)

diff --git a/lib/test_bpf.c b/lib/test_bpf.c
index ade9ac672adb..448bc1b0b8b5 100644
--- a/lib/test_bpf.c
+++ b/lib/test_bpf.c
@@ -14381,18 +14381,12 @@ static void *generate_test_data(struct bpf_test *test, int sub)
 		 * single fragment to the skb, filled with
 		 * test->frag_data.
 		 */
-		void *ptr;
-
 		page = alloc_page(GFP_KERNEL);
 
 		if (!page)
 			goto err_kfree_skb;
 
-		ptr = kmap(page);
-		if (!ptr)
-			goto err_free_page;
-		memcpy(ptr, test->frag_data, MAX_DATA);
-		kunmap(page);
+		memcpy(page_address(page), test->frag_data, MAX_DATA);
 		skb_add_rx_frag(skb, 0, page, 0, MAX_DATA, MAX_DATA);
 	}
 
-- 
2.25.1


^ permalink raw reply related	[flat|nested] 4+ messages in thread
end of thread, other threads:[~2023-06-26 20:36 UTC | newest]

Thread overview: 4+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2023-06-22  7:52 [PATCH v3] lib/test_bpf: Call page_address() on page acquired with GFP_KERNEL flag Sumitra Sharma
2023-06-26 20:36 ` Ira Weiny
  -- strict thread matches above, loose matches on Subject: below --
2023-06-22  8:07 Sumitra Sharma
2023-06-22 22:00 ` kernel test robot

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