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Message-ID: <20191114193925.GB24848@dhcp22.suse.cz>
Date: Thu, 14 Nov 2019 20:39:26 +0100
From: Michal Hocko <mhocko@...nel.org>
To: David Hildenbrand <david@...hat.com>
Cc: linux-kernel@...r.kernel.org, linux-mm@...ck.org,
linuxppc-dev@...ts.ozlabs.org,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
"Rafael J. Wysocki" <rafael@...nel.org>,
Andrew Morton <akpm@...ux-foundation.org>,
Pavel Tatashin <pasha.tatashin@...een.com>,
Dan Williams <dan.j.williams@...el.com>,
Oscar Salvador <osalvador@...e.de>, Qian Cai <cai@....pw>,
Anshuman Khandual <anshuman.khandual@....com>,
Pingfan Liu <kernelfans@...il.com>,
Michael Ellerman <mpe@...erman.id.au>
Subject: Re: [PATCH v2 1/2] mm: remove the memory isolate notifier
On Thu 14-11-19 14:19:10, David Hildenbrand wrote:
> Luckily, we have no users left, so we can get rid of it. Cleanup
> set_migratetype_isolate() a little bit.
>
> Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
> Cc: "Rafael J. Wysocki" <rafael@...nel.org>
> Cc: Andrew Morton <akpm@...ux-foundation.org>
> Cc: Pavel Tatashin <pasha.tatashin@...een.com>
> Cc: Michal Hocko <mhocko@...e.com>
> Cc: Dan Williams <dan.j.williams@...el.com>
> Cc: Oscar Salvador <osalvador@...e.de>
> Cc: Qian Cai <cai@....pw>
> Cc: Anshuman Khandual <anshuman.khandual@....com>
> Cc: Pingfan Liu <kernelfans@...il.com>
> Cc: Michael Ellerman <mpe@...erman.id.au>
> Signed-off-by: David Hildenbrand <david@...hat.com>
\o/
Acked-by: Michal Hocko <mhocko@...e.com>
There is some potential on a further cleanups but this is definitely a
great step
> ---
> drivers/base/memory.c | 19 -------------------
> include/linux/memory.h | 27 ---------------------------
> mm/page_isolation.c | 38 ++++----------------------------------
> 3 files changed, 4 insertions(+), 80 deletions(-)
>
> diff --git a/drivers/base/memory.c b/drivers/base/memory.c
> index a757d9ed88a7..03c18c97c2bf 100644
> --- a/drivers/base/memory.c
> +++ b/drivers/base/memory.c
> @@ -73,20 +73,6 @@ void unregister_memory_notifier(struct notifier_block *nb)
> }
> EXPORT_SYMBOL(unregister_memory_notifier);
>
> -static ATOMIC_NOTIFIER_HEAD(memory_isolate_chain);
> -
> -int register_memory_isolate_notifier(struct notifier_block *nb)
> -{
> - return atomic_notifier_chain_register(&memory_isolate_chain, nb);
> -}
> -EXPORT_SYMBOL(register_memory_isolate_notifier);
> -
> -void unregister_memory_isolate_notifier(struct notifier_block *nb)
> -{
> - atomic_notifier_chain_unregister(&memory_isolate_chain, nb);
> -}
> -EXPORT_SYMBOL(unregister_memory_isolate_notifier);
> -
> static void memory_block_release(struct device *dev)
> {
> struct memory_block *mem = to_memory_block(dev);
> @@ -178,11 +164,6 @@ int memory_notify(unsigned long val, void *v)
> return blocking_notifier_call_chain(&memory_chain, val, v);
> }
>
> -int memory_isolate_notify(unsigned long val, void *v)
> -{
> - return atomic_notifier_call_chain(&memory_isolate_chain, val, v);
> -}
> -
> /*
> * The probe routines leave the pages uninitialized, just as the bootmem code
> * does. Make sure we do not access them, but instead use only information from
> diff --git a/include/linux/memory.h b/include/linux/memory.h
> index 0ebb105eb261..d3fde2d0d94b 100644
> --- a/include/linux/memory.h
> +++ b/include/linux/memory.h
> @@ -55,19 +55,6 @@ struct memory_notify {
> int status_change_nid;
> };
>
> -/*
> - * During pageblock isolation, count the number of pages within the
> - * range [start_pfn, start_pfn + nr_pages) which are owned by code
> - * in the notifier chain.
> - */
> -#define MEM_ISOLATE_COUNT (1<<0)
> -
> -struct memory_isolate_notify {
> - unsigned long start_pfn; /* Start of range to check */
> - unsigned int nr_pages; /* # pages in range to check */
> - unsigned int pages_found; /* # pages owned found by callbacks */
> -};
> -
> struct notifier_block;
> struct mem_section;
>
> @@ -94,27 +81,13 @@ static inline int memory_notify(unsigned long val, void *v)
> {
> return 0;
> }
> -static inline int register_memory_isolate_notifier(struct notifier_block *nb)
> -{
> - return 0;
> -}
> -static inline void unregister_memory_isolate_notifier(struct notifier_block *nb)
> -{
> -}
> -static inline int memory_isolate_notify(unsigned long val, void *v)
> -{
> - return 0;
> -}
> #else
> extern int register_memory_notifier(struct notifier_block *nb);
> extern void unregister_memory_notifier(struct notifier_block *nb);
> -extern int register_memory_isolate_notifier(struct notifier_block *nb);
> -extern void unregister_memory_isolate_notifier(struct notifier_block *nb);
> int create_memory_block_devices(unsigned long start, unsigned long size);
> void remove_memory_block_devices(unsigned long start, unsigned long size);
> extern void memory_dev_init(void);
> extern int memory_notify(unsigned long val, void *v);
> -extern int memory_isolate_notify(unsigned long val, void *v);
> extern struct memory_block *find_memory_block(struct mem_section *);
> typedef int (*walk_memory_blocks_func_t)(struct memory_block *, void *);
> extern int walk_memory_blocks(unsigned long start, unsigned long size,
> diff --git a/mm/page_isolation.c b/mm/page_isolation.c
> index 04ee1663cdbe..21af88b718aa 100644
> --- a/mm/page_isolation.c
> +++ b/mm/page_isolation.c
> @@ -18,9 +18,7 @@
> static int set_migratetype_isolate(struct page *page, int migratetype, int isol_flags)
> {
> struct zone *zone;
> - unsigned long flags, pfn;
> - struct memory_isolate_notify arg;
> - int notifier_ret;
> + unsigned long flags;
> int ret = -EBUSY;
>
> zone = page_zone(page);
> @@ -35,41 +33,11 @@ static int set_migratetype_isolate(struct page *page, int migratetype, int isol_
> if (is_migrate_isolate_page(page))
> goto out;
>
> - pfn = page_to_pfn(page);
> - arg.start_pfn = pfn;
> - arg.nr_pages = pageblock_nr_pages;
> - arg.pages_found = 0;
> -
> - /*
> - * It may be possible to isolate a pageblock even if the
> - * migratetype is not MIGRATE_MOVABLE. The memory isolation
> - * notifier chain is used by balloon drivers to return the
> - * number of pages in a range that are held by the balloon
> - * driver to shrink memory. If all the pages are accounted for
> - * by balloons, are free, or on the LRU, isolation can continue.
> - * Later, for example, when memory hotplug notifier runs, these
> - * pages reported as "can be isolated" should be isolated(freed)
> - * by the balloon driver through the memory notifier chain.
> - */
> - notifier_ret = memory_isolate_notify(MEM_ISOLATE_COUNT, &arg);
> - notifier_ret = notifier_to_errno(notifier_ret);
> - if (notifier_ret)
> - goto out;
> /*
> * FIXME: Now, memory hotplug doesn't call shrink_slab() by itself.
> * We just check MOVABLE pages.
> */
> - if (!has_unmovable_pages(zone, page, arg.pages_found, migratetype,
> - isol_flags))
> - ret = 0;
> -
> - /*
> - * immobile means "not-on-lru" pages. If immobile is larger than
> - * removable-by-driver pages reported by notifier, we'll fail.
> - */
> -
> -out:
> - if (!ret) {
> + if (!has_unmovable_pages(zone, page, 0, migratetype, isol_flags)) {
> unsigned long nr_pages;
> int mt = get_pageblock_migratetype(page);
>
> @@ -79,8 +47,10 @@ static int set_migratetype_isolate(struct page *page, int migratetype, int isol_
> NULL);
>
> __mod_zone_freepage_state(zone, -nr_pages, mt);
> + ret = 0;
> }
>
> +out:
> spin_unlock_irqrestore(&zone->lock, flags);
> if (!ret)
> drain_all_pages(zone);
> --
> 2.21.0
--
Michal Hocko
SUSE Labs
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