From: David Hildenbrand <david@redhat.com>
To: Oscar Salvador <osalvador@suse.de>, akpm@linux-foundation.org
Cc: mhocko@suse.com, dan.j.williams@intel.com,
pasha.tatashin@soleen.com, Jonathan.Cameron@huawei.com,
anshuman.khandual@arm.com, vbabka@suse.cz, linux-mm@kvack.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2 1/5] drivers/base/memory: Remove unneeded check in remove_memory_block_devices
Date: Tue, 25 Jun 2019 10:03:31 +0200 [thread overview]
Message-ID: <0ed2f4ec-cc6f-8b81-46b0-d56d90ac1e86@redhat.com> (raw)
In-Reply-To: <3e820fee-f82f-3336-ff34-31c66dbbbbfe@redhat.com>
On 25.06.19 10:01, David Hildenbrand wrote:
> On 25.06.19 09:52, Oscar Salvador wrote:
>> remove_memory_block_devices() checks for the range to be aligned
>> to memory_block_size_bytes, which is our current memory block size,
>> and WARNs_ON and bails out if it is not.
>>
>> This is the right to do, but we do already do that in try_remove_memory(),
>> where remove_memory_block_devices() gets called from, and we even are
>> more strict in try_remove_memory, since we directly BUG_ON in case the range
>> is not properly aligned.
>>
>> Since remove_memory_block_devices() is only called from try_remove_memory(),
>> we can safely drop the check here.
>>
>> To be honest, I am not sure if we should kill the system in case we cannot
>> remove memory.
>> I tend to think that WARN_ON and return and error is better.
>
> I failed to parse this sentence.
>
>>
>> Signed-off-by: Oscar Salvador <osalvador@suse.de>
>> ---
>> drivers/base/memory.c | 4 ----
>> 1 file changed, 4 deletions(-)
>>
>> diff --git a/drivers/base/memory.c b/drivers/base/memory.c
>> index 826dd76f662e..07ba731beb42 100644
>> --- a/drivers/base/memory.c
>> +++ b/drivers/base/memory.c
>> @@ -771,10 +771,6 @@ void remove_memory_block_devices(unsigned long start, unsigned long size)
>> struct memory_block *mem;
>> int block_id;
>>
>> - if (WARN_ON_ONCE(!IS_ALIGNED(start, memory_block_size_bytes()) ||
>> - !IS_ALIGNED(size, memory_block_size_bytes())))
>> - return;
>> -
>> mutex_lock(&mem_sysfs_mutex);
>> for (block_id = start_block_id; block_id != end_block_id; block_id++) {
>> mem = find_memory_block_by_id(block_id, NULL);
>>
>
> As I said when I introduced this, I prefer to have such duplicate checks
> in place in case we have dependent code splattered over different files.
> (especially mm/ vs. drivers/base). Such simple checks avoid to document
> "start and size have to be aligned to memory blocks".
Lol, I even documented it as well. So yeah, if you're going to drop this
once, also drop the one in create_memory_block_devices().
>
> If you still insist, then also remove the same sequence from
> create_memory_block_devices().
>
--
Thanks,
David / dhildenb
next prev parent reply other threads:[~2019-06-25 8:03 UTC|newest]
Thread overview: 58+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-06-25 7:52 [PATCH v2 0/5] Allocate memmap from hotadded memory Oscar Salvador
2019-06-25 7:52 ` [PATCH v2 1/5] drivers/base/memory: Remove unneeded check in remove_memory_block_devices Oscar Salvador
2019-06-25 8:01 ` David Hildenbrand
2019-06-25 8:03 ` David Hildenbrand [this message]
2019-06-25 8:09 ` Oscar Salvador
2019-06-25 8:27 ` David Hildenbrand
2019-06-25 7:52 ` [PATCH v2 2/5] mm,memory_hotplug: Introduce MHP_VMEMMAP_FLAGS Oscar Salvador
2019-06-25 8:31 ` David Hildenbrand
2019-07-24 20:11 ` Dan Williams
2019-07-24 21:36 ` osalvador
2019-07-25 9:27 ` Oscar Salvador
2019-07-25 9:30 ` David Hildenbrand
2019-07-25 9:40 ` Oscar Salvador
2019-07-25 10:04 ` David Hildenbrand
2019-07-25 10:13 ` Oscar Salvador
2019-07-25 10:15 ` David Hildenbrand
2019-06-25 7:52 ` [PATCH v2 3/5] mm,memory_hotplug: Introduce Vmemmap page helpers Oscar Salvador
2019-06-25 10:28 ` David Hildenbrand
2019-06-26 9:48 ` Oscar Salvador
2019-06-25 7:52 ` [PATCH v2 4/5] mm,memory_hotplug: allocate memmap from the added memory range for sparse-vmemmap Oscar Salvador
2019-06-25 8:49 ` David Hildenbrand
2019-06-26 8:13 ` Oscar Salvador
2019-06-26 8:15 ` David Hildenbrand
2019-06-26 8:17 ` Anshuman Khandual
2019-06-26 8:28 ` Oscar Salvador
2019-07-24 21:49 ` Dan Williams
2019-06-25 7:52 ` [PATCH v2 5/5] mm,memory_hotplug: Allow userspace to enable/disable vmemmap Oscar Salvador
2019-06-25 8:25 ` [PATCH v2 0/5] Allocate memmap from hotadded memory David Hildenbrand
2019-06-25 8:33 ` David Hildenbrand
2019-06-26 8:03 ` Oscar Salvador
2019-06-26 8:11 ` David Hildenbrand
2019-06-26 8:15 ` Oscar Salvador
2019-06-26 8:27 ` Oscar Salvador
2019-06-26 8:37 ` David Hildenbrand
2019-06-26 8:28 ` David Hildenbrand
2019-07-02 6:42 ` Rashmica Gupta
2019-07-02 7:48 ` Oscar Salvador
2019-07-02 8:52 ` Rashmica Gupta
2019-07-10 1:14 ` Rashmica Gupta
2019-07-31 12:08 ` Michal Hocko
2019-07-31 23:06 ` Rashmica Gupta
2019-08-01 7:17 ` Michal Hocko
2019-08-01 7:18 ` David Hildenbrand
2019-08-01 7:24 ` Michal Hocko
2019-08-01 7:26 ` David Hildenbrand
2019-08-01 7:31 ` David Hildenbrand
2019-08-01 7:39 ` Michal Hocko
2019-08-01 7:48 ` Michal Hocko
2019-08-01 9:18 ` David Hildenbrand
2019-08-01 7:34 ` Michal Hocko
2019-08-01 7:50 ` David Hildenbrand
2019-08-01 8:04 ` Michal Hocko
2019-07-16 12:28 ` David Hildenbrand
2019-07-29 5:42 ` Rashmica Gupta
2019-07-29 8:06 ` David Hildenbrand
2019-07-30 7:08 ` Rashmica Gupta
2019-07-31 2:21 ` Rashmica Gupta
2019-07-31 9:39 ` David Hildenbrand
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