On 2024/8/21 19:28, David Hildenbrand wrote:
> On 21.08.24 09:53, Zhen Lei wrote:
>> When the debug information needs to be suppressed due to ratelimit,
>> it is unnecessary to determine the end of the corrupted memory.
>>
>> Signed-off-by: Zhen Lei <thunder.leizhen@xxxxxxxxxx>
>> ---
>> mm/page_poison.c | 7 ++++---
>> 1 file changed, 4 insertions(+), 3 deletions(-)
>>
>> diff --git a/mm/page_poison.c b/mm/page_poison.c
>> index 3e9037363cf9d85..23fa799214720f1 100644
>> --- a/mm/page_poison.c
>> +++ b/mm/page_poison.c
>> @@ -55,14 +55,15 @@ static void check_poison_mem(struct page *page, unsigned char *mem, size_t bytes
>> if (!start)
>> return;
>> + if (!__ratelimit(&ratelimit))
>> + return;
>> +
>> for (end = mem + bytes - 1; end > start; end--) {
>> if (*end != PAGE_POISON)
>> break;
>> }
>> - if (!__ratelimit(&ratelimit))
>> - return;
>> - else if (start == end && single_bit_flip(*start, PAGE_POISON))
>> + if (start == end && single_bit_flip(*start, PAGE_POISON))
>> pr_err("pagealloc: single bit error\n");
>> else
>> pr_err("pagealloc: memory corruption\n");
>
> This way, you will be ratelimiting on every function call, possibly skipping PAGE_POISON checks even if there was no prior corruption detected?
>
No, the previous memchr_inv() does the PAGE_POISON check, determine the start of the corrupted memory. !start means no corruption.
start = memchr_inv(mem, PAGE_POISON, bytes);
if (!start)
return;
+ if (!__ratelimit(&ratelimit))
+ return;
for (end = mem + bytes - 1; end > start; end--) {
if (*end != PAGE_POISON)
break;
}
--
Regards,
Zhen Lei
