On 28 May 2025, at 23:17, Dev Jain wrote:
> On 28/05/25 10:42 pm, Zi Yan wrote:
>> On 28 May 2025, at 7:31, Dev Jain wrote:
>>
>>> Suppose xas is pointing somewhere near the end of the multi-entry batch.
>>> Then it may happen that the computed slot already falls beyond the batch,
>>> thus breaking the loop due to !xa_is_sibling(), and computing the wrong
>>> order. Thus ensure that the caller is aware of this by triggering a BUG
>>> when the entry is a sibling entry.
>> Is it possible to add a test case in lib/test_xarray.c for this?
>> You can compile the tests with “make -C tools/testing/radix-tree”
>> and run “./tools/testing/radix-tree/xarray”.
>
>
> Sorry forgot to Cc you.
> I can surely do that later, but does this patch look fine?
I am not sure the exact situation you are describing, so I asked you
to write a test case to demonstrate the issue. :)
>
>
>>
>>> This patch is motivated by code inspection and not a real bug report.
>>>
>>> Signed-off-by: Dev Jain <dev.jain@xxxxxxx>
>>> ---
>>> The patch applies on 6.15 kernel.
>>>
>>> lib/xarray.c | 2 ++
>>> 1 file changed, 2 insertions(+)
>>>
>>> diff --git a/lib/xarray.c b/lib/xarray.c
>>> index 9644b18af18d..0f699766c24f 100644
>>> --- a/lib/xarray.c
>>> +++ b/lib/xarray.c
>>> @@ -1917,6 +1917,8 @@ int xas_get_order(struct xa_state *xas)
>>> if (!xas->xa_node)
>>> return 0;
>>>
>>> + XA_NODE_BUG_ON(xas->xa_node, xa_is_sibling(xa_entry(xas->xa,
>>> + xas->xa_node, xas->xa_offset)));
>>> for (;;) {
>>> unsigned int slot = xas->xa_offset + (1 << order);
>>>
>>> --
>>> 2.30.2
>>
>> Best Regards,
>> Yan, Zi
Best Regards,
Yan, Zi
