| Message ID | 20200307084229.28251-6-bhe@redhat.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | mm/hotplug: Only use subsection map for VMEMMAP | expand |
On 03/07/20 at 04:42pm, Baoquan He wrote: Sorry, the subject should be: mm/sparse.c: add note about only VMEMMAP supporting sub-section hotplug > And tell check_pfn_span() gating the porper alignment and size of > hot added memory region. > > And also move the code comments from inside section_deactivate() > to being above it. The code comments are reasonable for the whole > function, and the moving makes code cleaner. > > Signed-off-by: Baoquan He <bhe@redhat.com> > --- > mm/sparse.c | 37 ++++++++++++++++++++----------------- > 1 file changed, 20 insertions(+), 17 deletions(-) > > diff --git a/mm/sparse.c b/mm/sparse.c > index 2142045ab5c5..0fbd79c4ad81 100644 > --- a/mm/sparse.c > +++ b/mm/sparse.c > @@ -772,6 +772,22 @@ static bool is_subsection_map_empty(struct mem_section *ms) > } > #endif > > +/* > + * To deactivate a memory region, there are 3 cases to handle across > + * two configurations (SPARSEMEM_VMEMMAP={y,n}): > + * > + * 1. deactivation of a partial hot-added section (only possible in > + * the SPARSEMEM_VMEMMAP=y case). > + * a) section was present at memory init. > + * b) section was hot-added post memory init. > + * 2. deactivation of a complete hot-added section. > + * 3. deactivation of a complete section from memory init. > + * > + * For 1, when subsection_map does not empty we will not be freeing the > + * usage map, but still need to free the vmemmap range. > + * > + * For 2 and 3, the SPARSEMEM_VMEMMAP={y,n} cases are unified > + */ > static void section_deactivate(unsigned long pfn, unsigned long nr_pages, > struct vmem_altmap *altmap) > { > @@ -784,23 +800,6 @@ static void section_deactivate(unsigned long pfn, unsigned long nr_pages, > return; > > empty = is_subsection_map_empty(ms); > - /* > - * There are 3 cases to handle across two configurations > - * (SPARSEMEM_VMEMMAP={y,n}): > - * > - * 1/ deactivation of a partial hot-added section (only possible > - * in the SPARSEMEM_VMEMMAP=y case). > - * a/ section was present at memory init > - * b/ section was hot-added post memory init > - * 2/ deactivation of a complete hot-added section > - * 3/ deactivation of a complete section from memory init > - * > - * For 1/, when subsection_map does not empty we will not be > - * freeing the usage map, but still need to free the vmemmap > - * range. > - * > - * For 2/ and 3/ the SPARSEMEM_VMEMMAP={y,n} cases are unified > - */ > if (empty) { > unsigned long section_nr = pfn_to_section_nr(pfn); > > @@ -907,6 +906,10 @@ static struct page * __meminit section_activate(int nid, unsigned long pfn, > * > * This is only intended for hotplug. > * > + * Note that only VMEMMAP supports sub-section aligned hotplug, > + * the proper alignment and size are gated by check_pfn_span(). > + * > + * > * Return: > * * 0 - On success. > * * -EEXIST - Section has been present. > -- > 2.17.2 >
On Sat 07-03-20 16:42:27, Baoquan He wrote: > And tell check_pfn_span() gating the porper alignment and size of > hot added memory region. > > And also move the code comments from inside section_deactivate() > to being above it. The code comments are reasonable for the whole > function, and the moving makes code cleaner. > > Signed-off-by: Baoquan He <bhe@redhat.com> Acked-by: Michal Hocko <mhocko@suse.com> I have glanced through other patches and they seem sane but I do not have time to go deeper to give an ack. I like this one though because it really makes the intention clearer. > --- > mm/sparse.c | 37 ++++++++++++++++++++----------------- > 1 file changed, 20 insertions(+), 17 deletions(-) > > diff --git a/mm/sparse.c b/mm/sparse.c > index 2142045ab5c5..0fbd79c4ad81 100644 > --- a/mm/sparse.c > +++ b/mm/sparse.c > @@ -772,6 +772,22 @@ static bool is_subsection_map_empty(struct mem_section *ms) > } > #endif > > +/* > + * To deactivate a memory region, there are 3 cases to handle across > + * two configurations (SPARSEMEM_VMEMMAP={y,n}): > + * > + * 1. deactivation of a partial hot-added section (only possible in > + * the SPARSEMEM_VMEMMAP=y case). > + * a) section was present at memory init. > + * b) section was hot-added post memory init. > + * 2. deactivation of a complete hot-added section. > + * 3. deactivation of a complete section from memory init. > + * > + * For 1, when subsection_map does not empty we will not be freeing the > + * usage map, but still need to free the vmemmap range. > + * > + * For 2 and 3, the SPARSEMEM_VMEMMAP={y,n} cases are unified > + */ > static void section_deactivate(unsigned long pfn, unsigned long nr_pages, > struct vmem_altmap *altmap) > { > @@ -784,23 +800,6 @@ static void section_deactivate(unsigned long pfn, unsigned long nr_pages, > return; > > empty = is_subsection_map_empty(ms); > - /* > - * There are 3 cases to handle across two configurations > - * (SPARSEMEM_VMEMMAP={y,n}): > - * > - * 1/ deactivation of a partial hot-added section (only possible > - * in the SPARSEMEM_VMEMMAP=y case). > - * a/ section was present at memory init > - * b/ section was hot-added post memory init > - * 2/ deactivation of a complete hot-added section > - * 3/ deactivation of a complete section from memory init > - * > - * For 1/, when subsection_map does not empty we will not be > - * freeing the usage map, but still need to free the vmemmap > - * range. > - * > - * For 2/ and 3/ the SPARSEMEM_VMEMMAP={y,n} cases are unified > - */ > if (empty) { > unsigned long section_nr = pfn_to_section_nr(pfn); > > @@ -907,6 +906,10 @@ static struct page * __meminit section_activate(int nid, unsigned long pfn, > * > * This is only intended for hotplug. > * > + * Note that only VMEMMAP supports sub-section aligned hotplug, > + * the proper alignment and size are gated by check_pfn_span(). > + * > + * > * Return: > * * 0 - On success. > * * -EEXIST - Section has been present. > -- > 2.17.2 >
On 03/10/20 at 03:46pm, Michal Hocko wrote: > On Sat 07-03-20 16:42:27, Baoquan He wrote: > > And tell check_pfn_span() gating the porper alignment and size of > > hot added memory region. > > > > And also move the code comments from inside section_deactivate() > > to being above it. The code comments are reasonable for the whole > > function, and the moving makes code cleaner. > > > > Signed-off-by: Baoquan He <bhe@redhat.com> > > Acked-by: Michal Hocko <mhocko@suse.com> > > I have glanced through other patches and they seem sane but I do not > have time to go deeper to give an ack. I like this one though because it > really makes the intention clearer. Thanks for your reviewing and providing ack on this patch. I will post a new version to rebase on the top of patch 1 and its appended fix, then address those concerns from David.
diff --git a/mm/sparse.c b/mm/sparse.c index 2142045ab5c5..0fbd79c4ad81 100644 --- a/mm/sparse.c +++ b/mm/sparse.c @@ -772,6 +772,22 @@ static bool is_subsection_map_empty(struct mem_section *ms) } #endif +/* + * To deactivate a memory region, there are 3 cases to handle across + * two configurations (SPARSEMEM_VMEMMAP={y,n}): + * + * 1. deactivation of a partial hot-added section (only possible in + * the SPARSEMEM_VMEMMAP=y case). + * a) section was present at memory init. + * b) section was hot-added post memory init. + * 2. deactivation of a complete hot-added section. + * 3. deactivation of a complete section from memory init. + * + * For 1, when subsection_map does not empty we will not be freeing the + * usage map, but still need to free the vmemmap range. + * + * For 2 and 3, the SPARSEMEM_VMEMMAP={y,n} cases are unified + */ static void section_deactivate(unsigned long pfn, unsigned long nr_pages, struct vmem_altmap *altmap) { @@ -784,23 +800,6 @@ static void section_deactivate(unsigned long pfn, unsigned long nr_pages, return; empty = is_subsection_map_empty(ms); - /* - * There are 3 cases to handle across two configurations - * (SPARSEMEM_VMEMMAP={y,n}): - * - * 1/ deactivation of a partial hot-added section (only possible - * in the SPARSEMEM_VMEMMAP=y case). - * a/ section was present at memory init - * b/ section was hot-added post memory init - * 2/ deactivation of a complete hot-added section - * 3/ deactivation of a complete section from memory init - * - * For 1/, when subsection_map does not empty we will not be - * freeing the usage map, but still need to free the vmemmap - * range. - * - * For 2/ and 3/ the SPARSEMEM_VMEMMAP={y,n} cases are unified - */ if (empty) { unsigned long section_nr = pfn_to_section_nr(pfn); @@ -907,6 +906,10 @@ static struct page * __meminit section_activate(int nid, unsigned long pfn, * * This is only intended for hotplug. * + * Note that only VMEMMAP supports sub-section aligned hotplug, + * the proper alignment and size are gated by check_pfn_span(). + * + * * Return: * * 0 - On success. * * -EEXIST - Section has been present.
And tell check_pfn_span() gating the porper alignment and size of hot added memory region. And also move the code comments from inside section_deactivate() to being above it. The code comments are reasonable for the whole function, and the moving makes code cleaner. Signed-off-by: Baoquan He <bhe@redhat.com> --- mm/sparse.c | 37 ++++++++++++++++++++----------------- 1 file changed, 20 insertions(+), 17 deletions(-)