linux-kernel - Re: [RFC PATCH 4/4] XArray: test: Increase split order test range in check

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Message-ID: <diqzy0nc53au.fsf@google.com>
Date: Mon, 08 Dec 2025 08:47:05 -0800
From: Ackerley Tng <ackerleytng@...gle.com>
To: Zi Yan <ziy@...dia.com>
Cc: willy@...radead.org, akpm@...ux-foundation.org, 
	linux-fsdevel@...r.kernel.org, linux-mm@...ck.org, 
	linux-kernel@...r.kernel.org, david@...hat.com, michael.roth@....com, 
	vannapurve@...gle.com
Subject: Re: [RFC PATCH 4/4] XArray: test: Increase split order test range in check_split()

Zi Yan <ziy@...dia.com> writes:

> On 17 Nov 2025, at 17:47, Ackerley Tng wrote:
>
>> Expand the range of order values for check_split_1() from 2 *
>> XA_CHUNK_SHIFT to 4 * XA_CHUNK_SHIFT to test splitting beyond 2 levels.
>>
>> Separate the loops for check_split_1() and check_split_2() calls, since
>> xas_try_split() does not yet support splitting beyond 2 levels.
>
> xas_try_split() is designed to only split at most 1 level. It is used
> for non-uniform split, which always splits a folio from order N to order N-1.
>

Thanks for explaining! In the next revision, I'll rename

  + check_split_1() to check_split_uniform() and
  + check_split_2() to check_split_non_uniform()

in an earlier patch before, fixing the wording, in this patch, to be

  Separate the loops for check_split_uniform() and
  check_split_non_uniform() calls. Expanding the range of order values
  only applies for uniform splits, since non-uniform splits always split
  a folio from order N to order N-1.

>>
>> Signed-off-by: Ackerley Tng <ackerleytng@...gle.com>
>> ---
>>  lib/test_xarray.c | 6 +++++-
>>  1 file changed, 5 insertions(+), 1 deletion(-)
>>
>> diff --git a/lib/test_xarray.c b/lib/test_xarray.c
>> index 42626fb4dc0e..fbdf647e4ef8 100644
>> --- a/lib/test_xarray.c
>> +++ b/lib/test_xarray.c
>> @@ -1905,12 +1905,16 @@ static noinline void check_split(struct xarray *xa)
>>
>>  	XA_BUG_ON(xa, !xa_empty(xa));
>>
>> -	for (order = 1; order < 2 * XA_CHUNK_SHIFT; order++) {
>> +	for (order = 1; order < 4 * XA_CHUNK_SHIFT; order++) {
>>  		for (new_order = 0; new_order < order; new_order++) {
>>  			check_split_1(xa, 0, order, new_order);
>>  			check_split_1(xa, 1UL << order, order, new_order);
>>  			check_split_1(xa, 3UL << order, order, new_order);
>> +		}
>> +	}
>>
>> +	for (order = 1; order < 2 * XA_CHUNK_SHIFT; order++) {
>> +		for (new_order = 0; new_order < order; new_order++) {
>>  			check_split_2(xa, 0, order, new_order);
>>  			check_split_2(xa, 1UL << order, order, new_order);
>>  			check_split_2(xa, 3UL << order, order, new_order);
>> --
>> 2.52.0.rc1.455.g30608eb744-goog
>
>
> --
> Best Regards,
> Yan, Zi