Re: [PATCH v4 1/2] Revert "powerpc: Set max_mapnr correctly"

From: Christophe Leroy <christophe.leroy@csgroup.eu>
To: Kefeng Wang <wangkefeng.wang@huawei.com>,
	"linuxppc-dev@lists.ozlabs.org" <linuxppc-dev@lists.ozlabs.org>,
	"mpe@ellerman.id.au" <mpe@ellerman.id.au>,
	"benh@kernel.crashing.or" <benh@kernel.crashing.or>,
	"paulus@samba.org" <paulus@samba.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"linux-mm@kvack.org" <linux-mm@kvack.org>
Cc: "akpm@linux-foundation.org" <akpm@linux-foundation.org>,
	"npiggin@gmail.com" <npiggin@gmail.com>,
	"songyuanzheng@huawei.com" <songyuanzheng@huawei.com>
Subject: Re: [PATCH v4 1/2] Revert "powerpc: Set max_mapnr correctly"
Date: Mon, 28 Mar 2022 14:12:06 +0000	[thread overview]
Message-ID: <de3e12e2-6dff-90cd-3f47-fe8deaae1fa8@csgroup.eu> (raw)
In-Reply-To: <b2ff771c-01ef-3f14-f22d-9248735fdc77@huawei.com>

Hi,

Le 26/03/2022 à 08:55, Kefeng Wang a écrit :
> Hi maintainers，
> 
> I saw the patches has been reviewed[1], could they be merged?

Thinking about it once more, I think the patches should go in reverse 
order. Patch 2 should go first and patch 1 should go after.

Otherwise, once patch 1 is applied and patch 2 is not applied yet, 
virt_addr_valid() doesn't work anymore.

Christophe

> 
> Many thanks.
> 
> [1] https://patchwork.ozlabs.org/project/linuxppc-dev/list/?series=286464
> 
> On 2022/2/16 20:11, Kefeng Wang wrote:
>> This reverts commit 602946ec2f90d5bd965857753880db29d2d9a1e9.
>>
>> If CONFIG_HIGHMEM enabled, highmem will be disappeared with max_mapnr
>> set to max_low_pfn, see mem_init(),
>>
>>    for (pfn = highmem_mapnr; pfn < max_mapnr; ++pfn) {
>>          ...
>>     free_highmem_page();
>>    }
>>
>> Revert it and will fix virt_addr_valid() check in the next patch.
>>
>> Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
>> Fixes: 602946ec2f90 ("powerpc: Set max_mapnr correctly")
>> Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
>> ---
>> v4:
>> - new patch
>>   arch/powerpc/mm/mem.c | 2 +-
>>   1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/arch/powerpc/mm/mem.c b/arch/powerpc/mm/mem.c
>> index 8e301cd8925b..4d221d033804 100644
>> --- a/arch/powerpc/mm/mem.c
>> +++ b/arch/powerpc/mm/mem.c
>> @@ -255,7 +255,7 @@ void __init mem_init(void)
>>   #endif
>>       high_memory = (void *) __va(max_low_pfn * PAGE_SIZE);
>> -    set_max_mapnr(max_low_pfn);
>> +    set_max_mapnr(max_pfn);
>>       kasan_late_init();