linux-kernel - Re: [PATCH v3 1/6] binder: Fix selftest page indexing

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Message-ID: <dbx8ldon6b8v.fsf@ynaffit-andsys.c.googlers.com>
Date: Wed, 16 Jul 2025 15:07:12 -0700
From: Tiffany Yang <ynaffit@...gle.com>
To: Kees Cook <kees@...nel.org>
Cc: linux-kernel@...r.kernel.org, kernel-team@...roid.com, 
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>, 
	"Arve Hjønnevåg" <arve@...roid.com>, Todd Kjos <tkjos@...roid.com>, Martijn Coenen <maco@...roid.com>, 
	Joel Fernandes <joelagnelf@...dia.com>, Christian Brauner <brauner@...nel.org>, 
	Carlos Llamas <cmllamas@...gle.com>, Suren Baghdasaryan <surenb@...gle.com>, 
	Brendan Higgins <brendan.higgins@...ux.dev>, David Gow <davidgow@...gle.com>, 
	Rae Moar <rmoar@...gle.com>, linux-kselftest@...r.kernel.org, 
	kunit-dev@...glegroups.com
Subject: Re: [PATCH v3 1/6] binder: Fix selftest page indexing

Kees Cook <kees@...nel.org> writes:

> On Mon, Jul 14, 2025 at 11:53:14AM -0700, Tiffany Yang wrote:
>> The binder allocator selftest was only checking the last page of buffers
>> that ended on a page boundary. Correct the page indexing to account for
>> buffers that are not page-aligned.

>> Signed-off-by: Tiffany Yang <ynaffit@...gle.com>
>> ---
>>   drivers/android/binder_alloc_selftest.c | 2 +-
>>   1 file changed, 1 insertion(+), 1 deletion(-)

>> diff --git a/drivers/android/binder_alloc_selftest.c  
>> b/drivers/android/binder_alloc_selftest.c
>> index c88735c54848..486af3ec3c02 100644
>> --- a/drivers/android/binder_alloc_selftest.c
>> +++ b/drivers/android/binder_alloc_selftest.c
>> @@ -142,12 +142,12 @@ static void binder_selftest_free_buf(struct  
>> binder_alloc *alloc,
>>   	for (i = 0; i < BUFFER_NUM; i++)
>>   		binder_alloc_free_buf(alloc, buffers[seq[i]]);

>> -	for (i = 0; i < end / PAGE_SIZE; i++) {
>>   		/**
>>   		 * Error message on a free page can be false positive
>>   		 * if binder shrinker ran during binder_alloc_free_buf
>>   		 * calls above.
>>   		 */
>> +	for (i = 0; i <= (end - 1) / PAGE_SIZE; i++) {

> Nit: this comment is now not aligned correctly. Probably the best would
> be the leave the "for" line above the comment.

> -Kees


Thank you for catching this! Will be fixed in v4.

>>   		if (list_empty(page_to_lru(alloc->pages[i]))) {
>>   			pr_err_size_seq(sizes, seq);
>>   			pr_err("expect lru but is %s at page index %d\n",
>> --
>> 2.50.0.727.gbf7dc18ff4-goog


-- 
Tiffany Y. Yang