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Message-ID: <108c55df-ac3f-c014-d79e-146cda1e80f6@redhat.com>
Date: Thu, 17 Oct 2019 10:02:55 +0200
From: David Hildenbrand <david@...hat.com>
To: Naoya Horiguchi <n-horiguchi@...jp.nec.com>
Cc: Naoya Horiguchi <nao.horiguchi@...il.com>,
"linux-mm@...ck.org" <linux-mm@...ck.org>,
Michal Hocko <mhocko@...nel.org>,
Oscar Salvador <osalvador@...e.de>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [PATCH] mm, soft-offline: convert parameter to pfn
On 17.10.19 09:50, Naoya Horiguchi wrote:
> On Thu, Oct 17, 2019 at 09:16:42AM +0200, David Hildenbrand wrote:
>> On 17.10.19 01:47, Naoya Horiguchi wrote:
>>> On Wed, Oct 16, 2019 at 10:57:57AM +0200, David Hildenbrand wrote:
>>>> On 16.10.19 10:54, Naoya Horiguchi wrote:
>>>>> On Wed, Oct 16, 2019 at 10:34:52AM +0200, David Hildenbrand wrote:
>>>>>> On 16.10.19 10:27, Naoya Horiguchi wrote:
>>>>>>> On Wed, Oct 16, 2019 at 09:56:19AM +0200, David Hildenbrand wrote:
>>>>>>>> On 16.10.19 09:09, Naoya Horiguchi wrote:
>>>>>>>>> Hi,
>>>>>>>>>
>>>>>>>>> I wrote a simple cleanup for parameter of soft_offline_page(),
>>>>>>>>> based on thread https://lkml.org/lkml/2019/10/11/57.
>>>>>>>>>
>>>>>>>>> I know that we need more cleanup on hwpoison-inject, but I think
>>>>>>>>> that will be mentioned in re-write patchset Oscar is preparing now.
>>>>>>>>> So let me shared only this part as a separate one now.
>>>>>>> ...
>>>>>>>>
>>>>>>>> I think you should rebase that patch on linux-next (where the
>>>>>>>> pfn_to_online_page() check is in place). I assume you'll want to move the
>>>>>>>> pfn_to_online_page() check into soft_offline_page() then as well?
>>>>>>>
>>>>>>> I rebased to next-20191016. And yes, we will move pfn_to_online_page()
>>>>>>> into soft offline code. It seems that we can also move pfn_valid(),
>>>>>>> but is simply moving like below good enough for you?
>>>>>>
>>>>>> At least I can't am the patch to current next/master (due to
>>>>>> pfn_to_online_page()).
>>>>
>>>> Could also be that my "git am" skills failed as the mail was not a
>>>> proper patch itself :)
>>>
>>> Sorry for the inconvenience, my company email system breaks original
>>> message by introducing quoted-printable format ('=20' or '=3D').
>>> Most mail client usually handles it but git-am doesn't.
>>> I give up using it and send via smtp.gmail.com.
>>>
>>>>> @@ -1877,11 +1877,17 @@ static int soft_offline_free_page(struct page *page)
>>>>> * This is not a 100% solution for all memory, but tries to be
>>>>> * ``good enough'' for the majority of memory.
>>>>> */
>>>>> -int soft_offline_page(struct page *page, int flags)
>>>>> +int soft_offline_page(unsigned long pfn, int flags)
>>>>> {
>>>>> int ret;
>>>>> - unsigned long pfn = page_to_pfn(page);
>>>>> + struct page *page;
>>>>> + if (!pfn_valid(pfn))
>>>>> + return -ENXIO;
>>>>> + /* Only online pages can be soft-offlined (esp., not ZONE_DEVICE). */
>>>>> + page = pfn_to_online_page(pfn);
>>>>> + if (!page)
>>>>> + return -EIO;
>>>>> if (is_zone_device_page(page)) {
>>>>
>>>> -> this is now no longer possible! So you can drop the whole if
>>>> (is_zone_device....) case
>>>
>>> OK, thanks. I updated it.
>>>
>>> Thanks,
>>> Naoya Horiguchi
>>> ---
>>> From 5faf227839b578726fe7f5ff414a153abb3b3a31 Mon Sep 17 00:00:00 2001
>>> From: Naoya Horiguchi <n-horiguchi@...jp.nec.com>
>>> Date: Thu, 17 Oct 2019 08:40:53 +0900
>>> Subject: [PATCH] mm, soft-offline: convert parameter to pfn
>>>
>>> Currently soft_offline_page() receives struct page, and its sibling
>>> memory_failure() receives pfn. This discrepancy looks weird and makes
>>> precheck on pfn validity tricky. So let's align them.
>>>
>>> Signed-off-by: Naoya Horiguchi <n-horiguchi@...jp.nec.com>
>>> ---
>>> drivers/base/memory.c | 7 +------
>>> include/linux/mm.h | 2 +-
>>> mm/madvise.c | 2 +-
>>> mm/memory-failure.c | 19 +++++++++----------
>>> 4 files changed, 12 insertions(+), 18 deletions(-)
>>>
>>> diff --git a/drivers/base/memory.c b/drivers/base/memory.c
>>> index 55907c27075b..a757d9ed88a7 100644
>>> --- a/drivers/base/memory.c
>>> +++ b/drivers/base/memory.c
>>> @@ -538,12 +538,7 @@ static ssize_t soft_offline_page_store(struct device *dev,
>>> if (kstrtoull(buf, 0, &pfn) < 0)
>>> return -EINVAL;
>>> pfn >>= PAGE_SHIFT;
>>> - if (!pfn_valid(pfn))
>>> - return -ENXIO;
>>> - /* Only online pages can be soft-offlined (esp., not ZONE_DEVICE). */
>>> - if (!pfn_to_online_page(pfn))
>>> - return -EIO;
>>> - ret = soft_offline_page(pfn_to_page(pfn), 0);
>>> + ret = soft_offline_page(pfn, 0);
>>> return ret == 0 ? count : ret;
>>> }
>>> diff --git a/include/linux/mm.h b/include/linux/mm.h
>>> index 44d058723db9..fd360d208346 100644
>>> --- a/include/linux/mm.h
>>> +++ b/include/linux/mm.h
>>> @@ -2794,7 +2794,7 @@ extern int sysctl_memory_failure_early_kill;
>>> extern int sysctl_memory_failure_recovery;
>>> extern void shake_page(struct page *p, int access);
>>> extern atomic_long_t num_poisoned_pages __read_mostly;
>>> -extern int soft_offline_page(struct page *page, int flags);
>>> +extern int soft_offline_page(unsigned long pfn, int flags);
>>> /*
>>> diff --git a/mm/madvise.c b/mm/madvise.c
>>> index 2be9f3fdb05e..99dd06fecfa9 100644
>>> --- a/mm/madvise.c
>>> +++ b/mm/madvise.c
>>> @@ -887,7 +887,7 @@ static int madvise_inject_error(int behavior,
>>> pr_info("Soft offlining pfn %#lx at process virtual address %#lx\n",
>>> pfn, start);
>>> - ret = soft_offline_page(page, MF_COUNT_INCREASED);
>>> + ret = soft_offline_page(pfn, MF_COUNT_INCREASED);
>>> if (ret)
>>> return ret;
>>> continue;
>>> diff --git a/mm/memory-failure.c b/mm/memory-failure.c
>>> index 05c8c6df25e6..af2712004a4d 100644
>>> --- a/mm/memory-failure.c
>>> +++ b/mm/memory-failure.c
>>> @@ -1476,7 +1476,7 @@ static void memory_failure_work_func(struct work_struct *work)
>>> if (!gotten)
>>> break;
>>> if (entry.flags & MF_SOFT_OFFLINE)
>>> - soft_offline_page(pfn_to_page(entry.pfn), entry.flags);
>>> + soft_offline_page(entry.pfn, entry.flags);
>>> else
>>> memory_failure(entry.pfn, entry.flags);
>>> }
>>> @@ -1857,7 +1857,7 @@ static int soft_offline_free_page(struct page *page)
>>> /**
>>> * soft_offline_page - Soft offline a page.
>>> - * @page: page to offline
>>> + * @pfn: pfn to soft-offline
>>> * @flags: flags. Same as memory_failure().
>>> *
>>> * Returns 0 on success, otherwise negated errno.
>>> @@ -1877,18 +1877,17 @@ static int soft_offline_free_page(struct page *page)
>>> * This is not a 100% solution for all memory, but tries to be
>>> * ``good enough'' for the majority of memory.
>>> */
>>> -int soft_offline_page(struct page *page, int flags)
>>> +int soft_offline_page(unsigned long pfn, int flags)
>>> {
>>> int ret;
>>> - unsigned long pfn = page_to_pfn(page);
>>> + struct page *page;
>>> - if (is_zone_device_page(page)) {
>>> - pr_debug_ratelimited("soft_offline: %#lx page is device page\n",
>>> - pfn);
>>> - if (flags & MF_COUNT_INCREASED)
>>> - put_page(page);
>>> + if (!pfn_valid(pfn))
>>> + return -ENXIO;
>>> + /* Only online pages can be soft-offlined (esp., not ZONE_DEVICE). */
>>> + page = pfn_to_online_page(pfn);
>>> + if (!page)
>>
>> If you pass in a PFN with MF_COUNT_INCREASED via mm/madvise.c, you would now
>> no longer do a put_page(page) in case of ZONE_DEVICE (!page =
>> pfn_to_online_page(pfn);)
>
> Yes, right.
>
>>
>> something like this
>>
>> page = pfn_to_online_page(pfn);
>> if (!page) {
>> /*
>> * With MF_COUNT_INCREASED, we can use pfn_to_page() directly
>> * (esp., ZONE_DEVICE).
>> */
>> if (flags & MF_COUNT_INCREASED)
>> put_page(pfn_to_page(page));
>> return -EIO;
>> }
>>
>> For !pfn_valid(pfn), this is not relevant.
>
> Actually I guess that !pfn_valid() never happens when called from
> madvise_inject_error(), because madvise_inject_error() gets pfn via
> get_user_pages_fast() which only returns valid page for valid pfn.
>
> And we plan to remove MF_COUNT_INCREASED by Oscar's re-design work,
> so I start feeling that this patch should come on top of his tree.
I agree, let's clean that up first.
--
Thanks,
David / dhildenb
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