From: Ritesh Harjani (IBM) <ritesh.list@gmail•com>
To: Christophe Leroy <christophe.leroy@csgroup•eu>,
linuxppc-dev@lists•ozlabs.org
Cc: Michael Ellerman <mpe@ellerman•id.au>,
Madhavan Srinivasan <maddy@linux•ibm.com>
Subject: Re: [PATCH] powerpc: Use printk instead of WARN in change_memory_attr
Date: Tue, 27 Aug 2024 21:36:45 +0530 [thread overview]
Message-ID: <875xrmrluy.fsf@gmail.com> (raw)
In-Reply-To: <a09687b8-184c-40bf-bf5f-b9639dd6d136@csgroup.eu>
Christophe Leroy <christophe.leroy@csgroup•eu> writes:
> Le 27/08/2024 à 11:12, Ritesh Harjani (IBM) a écrit :
>> [Vous ne recevez pas souvent de courriers de ritesh.list@gmail•com. Découvrez pourquoi ceci est important à https://aka.ms/LearnAboutSenderIdentification ]
>>
>> Use pr_warn_once instead of WARN_ON_ONCE as discussed here [1]
>> for printing possible use of set_memory_* on linear map on Hash.
>>
>> [1]: https://lore.kernel.org/all/877cc2fpi2.fsf@mail.lhotse/#t
>>
>> Signed-off-by: Ritesh Harjani (IBM) <ritesh.list@gmail•com>
>> ---
>> arch/powerpc/mm/pageattr.c | 5 ++++-
>> 1 file changed, 4 insertions(+), 1 deletion(-)
>>
>> diff --git a/arch/powerpc/mm/pageattr.c b/arch/powerpc/mm/pageattr.c
>> index ac22bf28086f..c8c2d664c6f3 100644
>> --- a/arch/powerpc/mm/pageattr.c
>> +++ b/arch/powerpc/mm/pageattr.c
>> @@ -94,8 +94,11 @@ int change_memory_attr(unsigned long addr, int numpages, long action)
>> if (!radix_enabled()) {
>> int region = get_region_id(addr);
>>
>> - if (WARN_ON_ONCE(region != VMALLOC_REGION_ID && region != IO_REGION_ID))
>> + if (region != VMALLOC_REGION_ID && region != IO_REGION_ID) {
>> + pr_warn_once("%s: possible use of set_memory_* on linear map on Hash from (%ps)\n",
>> + __func__, __builtin_return_address(0));
>
> Is it really only linear map ?
>
> What about "possible user of set_memory_* outside of vmalloc or io region.
"warning: possible user of set_memory_* outside of vmalloc and io region."
I am thinking of adding a word "warning" too. I can make above change and send v2.
>
> Maybe a show_stack() would also be worth it ?
IMO, since we have the caller, we need not pollute the dmesg with the
entire call stack. Besides I am not aware of dump_stack_once() style prints.
>
>
> But in principle I think it would be better to keep the WARN_ONCE until
> we can add __must_check to set_memory_xxx() functions to be sure all
> callers check the result, as mandated by
> https://github.com/KSPP/linux/issues/7
Fixing the callers to check the return value is something that need not
depend on this change no?
The intention of this change is to mainly remove the heavy WARN_ON_ONCE
from powerpc specific change_memory_attr() and convert to printk warn.
-ritesh
next prev parent reply other threads:[~2024-08-27 16:25 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-08-27 9:12 [PATCH] powerpc: Use printk instead of WARN in change_memory_attr Ritesh Harjani (IBM)
2024-08-27 14:41 ` Christophe Leroy
2024-08-27 16:06 ` Ritesh Harjani [this message]
2024-08-30 11:13 ` Michael Ellerman
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