Re: [PATCH 1/1] time/jiffies: Fix conversion breakage on systems where USER_HZ < HZ

[Gerd Rausch <gerd.rausch@oracle.com>]

Hi Joel,

On 2026-02-27 07:03, Joel Granados wrote:
> On Wed, Feb 25, 2026 at 03:37:49PM -0800, Gerd Rausch wrote:
>> Conversion from user_hz to jiffies broke with
>> commit 2dc164a48e6fd ("sysctl: Create converter functions with two new macros")
>>
>> because the old overflow check in do_proc_dointvec_userhz_jiffies_conv()
>> to see if "*u_ptr" was too large got replaced by an unconditional:
>>      +    if (USER_HZ < HZ)
>>      +        return -EINVAL;
>>
>> which will always be true on platforms with "USER_HZ < HZ".
>>
>> We shouldn't need this extra check anyway, because clock_t_to_jiffies()
>> returns ULONG_MAX for the overflow case:
>>      if (x >= ~0UL / (HZ / USER_HZ))
>>          return ~0UL;
>>
>> and proc_int_u2k_conv_uop() checks for "> INT_MAX" after conversion:
>>      if (u > (ulong) INT_MAX)
>>          return -EINVAL;
>>
>> Fixes: 2dc164a48e6fd ("sysctl: Create converter functions with two new macros")
>> Reported-by: Colm Harrington <colm.harrington@oracle.com>
>> Signed-off-by: Gerd Rausch <gerd.rausch@oracle.com>
> I changed the message of the patch a bit. You can take a look here [1]
> 
> Best
> 
> [1] https://git.kernel.org/pub/scm/linux/kernel/git/sysctl/sysctl.git/commit/?h=sysctl-next&id=a17a86da1c90b62866bf2f45560510f2f6f18503
> 

Looks good to me.

Thanks for adding this fix,

   Gerd