From: David Hildenbrand <david@redhat.com>
To: Baoquan He <bhe@redhat.com>, linux-kernel@vger.kernel.org
Cc: linux-mm@kvack.org, akpm@linux-foundation.org,
richardw.yang@linux.intel.com, osalvador@suse.de,
dan.j.williams@intel.com, mhocko@suse.com, rppt@linux.ibm.com,
robin.murphy@arm.com
Subject: Re: [PATCH v2 3/7] mm/sparse.c: introduce a new function clear_subsection_map()
Date: Fri, 28 Feb 2020 15:36:54 +0100 [thread overview]
Message-ID: <dc5ab1b1-65e2-e20f-66aa-b71d739a5b6d@redhat.com> (raw)
In-Reply-To: <20200220043316.19668-4-bhe@redhat.com>
On 20.02.20 05:33, Baoquan He wrote:
> Wrap the codes which clear subsection map of one memory region from
> section_deactivate() into clear_subsection_map().
>
> Signed-off-by: Baoquan He <bhe@redhat.com>
> ---
> mm/sparse.c | 46 ++++++++++++++++++++++++++++++++++++++--------
> 1 file changed, 38 insertions(+), 8 deletions(-)
>
> diff --git a/mm/sparse.c b/mm/sparse.c
> index 977b47acd38d..df857ee9330c 100644
> --- a/mm/sparse.c
> +++ b/mm/sparse.c
> @@ -726,14 +726,25 @@ static void free_map_bootmem(struct page *memmap)
> }
> #endif /* CONFIG_SPARSEMEM_VMEMMAP */
>
> -static void section_deactivate(unsigned long pfn, unsigned long nr_pages,
> - struct vmem_altmap *altmap)
> +/**
> + * clear_subsection_map - Clear subsection map of one memory region
> + *
> + * @pfn - start pfn of the memory range
> + * @nr_pages - number of pfns to add in the region
> + *
> + * This is only intended for hotplug, and clear the related subsection
> + * map inside one section.
> + *
> + * Return:
> + * * -EINVAL - Section already deactived.
> + * * 0 - Subsection map is emptied.
> + * * 1 - Subsection map is not empty.
> + */
Less verbose please (in my preference: none and simplify return handling)
> +static int clear_subsection_map(unsigned long pfn, unsigned long nr_pages)
> {
> DECLARE_BITMAP(map, SUBSECTIONS_PER_SECTION) = { 0 };
> DECLARE_BITMAP(tmp, SUBSECTIONS_PER_SECTION) = { 0 };
> struct mem_section *ms = __pfn_to_section(pfn);
> - bool section_is_early = early_section(ms);
> - struct page *memmap = NULL;
> unsigned long *subsection_map = ms->usage
> ? &ms->usage->subsection_map[0] : NULL;
>
> @@ -744,8 +755,28 @@ static void section_deactivate(unsigned long pfn, unsigned long nr_pages,
> if (WARN(!subsection_map || !bitmap_equal(tmp, map, SUBSECTIONS_PER_SECTION),
> "section already deactivated (%#lx + %ld)\n",
> pfn, nr_pages))
> - return;
> + return -EINVAL;
> +
> + bitmap_xor(subsection_map, map, subsection_map, SUBSECTIONS_PER_SECTION);
>
> + if (bitmap_empty(subsection_map, SUBSECTIONS_PER_SECTION))
> + return 0;
> +
Can we please just have a
subsection_map_empty() instead and handle that in the caller?
(you can then always return true in the !VMEMMAP variant)
I dislike the "rc" handling in the caller.
> + return 1;
> +}
> +
> +static void section_deactivate(unsigned long pfn, unsigned long nr_pages,
> + struct vmem_altmap *altmap)
> +{
> + struct mem_section *ms = __pfn_to_section(pfn);
> + bool section_is_early = early_section(ms);
> + struct page *memmap = NULL;
> + int rc;
> +
> +
one superfluous empty line
> + rc = clear_subsection_map(pfn, nr_pages);
> + if (IS_ERR_VALUE((unsigned long)rc))
huh? "if (rc < 0)" ? or am I missing something?
> + return;
> /*
> * There are 3 cases to handle across two configurations
> * (SPARSEMEM_VMEMMAP={y,n}):
> @@ -763,8 +794,7 @@ static void section_deactivate(unsigned long pfn, unsigned long nr_pages,
> *
> * For 2/ and 3/ the SPARSEMEM_VMEMMAP={y,n} cases are unified
> */
> - bitmap_xor(subsection_map, map, subsection_map, SUBSECTIONS_PER_SECTION);
> - if (bitmap_empty(subsection_map, SUBSECTIONS_PER_SECTION)) {
> + if (!rc) {
> unsigned long section_nr = pfn_to_section_nr(pfn);
>
> /*
> @@ -786,7 +816,7 @@ static void section_deactivate(unsigned long pfn, unsigned long nr_pages,
> else
> depopulate_section_memmap(pfn, nr_pages, altmap);
>
> - if (bitmap_empty(subsection_map, SUBSECTIONS_PER_SECTION))
> + if (!rc)
I don't really like that handling.
Either
s/rc/section_empty/
or use a separate subsection_map_empty()
> ms->section_mem_map = (unsigned long)NULL;
> }
>
>
Thanks!
--
Thanks,
David / dhildenb
next prev parent reply other threads:[~2020-02-28 14:37 UTC|newest]
Thread overview: 45+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-20 4:33 [PATCH v2 0/7] mm/hotplug: Only use subsection map in VMEMMAP case Baoquan He
2020-02-20 4:33 ` [PATCH v2 1/7] mm/hotplug: fix hot remove failure in SPARSEMEM|!VMEMMAP case Baoquan He
2020-02-20 6:11 ` Wei Yang
2020-02-20 12:07 ` David Hildenbrand
2020-02-26 12:31 ` David Hildenbrand
2020-02-26 13:07 ` Baoquan He
2020-02-26 18:09 ` Dan Williams
2020-03-03 8:34 ` David Hildenbrand
2020-03-03 8:39 ` Baoquan He
2020-02-20 4:33 ` [PATCH v2 2/7] mm/sparse.c: introduce new function fill_subsection_map() Baoquan He
2020-02-20 6:14 ` Wei Yang
2020-02-28 14:27 ` David Hildenbrand
2020-03-01 4:59 ` Baoquan He
2020-02-20 4:33 ` [PATCH v2 3/7] mm/sparse.c: introduce a new function clear_subsection_map() Baoquan He
2020-02-20 6:15 ` Wei Yang
2020-02-28 14:36 ` David Hildenbrand [this message]
2020-03-01 5:20 ` Baoquan He
2020-03-02 15:43 ` David Hildenbrand
2020-03-03 1:53 ` Baoquan He
2020-03-03 8:22 ` Baoquan He
2020-03-03 8:33 ` David Hildenbrand
2020-03-03 8:38 ` Baoquan He
2020-02-20 4:33 ` [PATCH v2 4/7] mm/sparse.c: only use subsection map in VMEMMAP case Baoquan He
2020-02-20 6:17 ` Wei Yang
2020-02-25 9:57 ` Michal Hocko
2020-02-26 3:53 ` Baoquan He
2020-02-26 9:10 ` Michal Hocko
2020-02-28 7:25 ` Baoquan He
2020-02-20 4:33 ` [PATCH v2 5/7] mm/sparse.c: add code comment about sub-section hotplug Baoquan He
2020-02-20 4:33 ` [PATCH v2 6/7] mm/sparse.c: move subsection_map related codes together Baoquan He
2020-02-20 6:18 ` Wei Yang
2020-02-20 7:04 ` Baoquan He
2020-02-20 7:12 ` Wei Yang
2020-02-20 8:55 ` Baoquan He
2020-02-20 21:52 ` Wei Yang
2020-02-20 4:33 ` [PATCH v2 7/7] mm/sparse.c: Use __get_free_pages() instead in populate_section_memmap() Baoquan He
2020-02-20 10:38 ` [PATCH v2 0/7] mm/hotplug: Only use subsection map in VMEMMAP case Michal Hocko
2020-02-21 14:28 ` Baoquan He
2020-02-25 9:10 ` David Hildenbrand
2020-02-25 10:02 ` Michal Hocko
2020-02-26 3:42 ` Baoquan He
2020-02-26 9:14 ` Michal Hocko
2020-02-26 12:30 ` Baoquan He
2020-02-25 10:03 ` Michal Hocko
2020-02-26 3:44 ` Baoquan He
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