| Message ID | 1541665398-29925-5-git-send-email-arunks@codeaurora.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | mm: convert totalram_pages, totalhigh_pages and managed pages to atomic | expand |
On Thu 08-11-18 13:53:18, Arun KS wrote: > Now totalram_pages and managed_pages are atomic varibles. No need > of managed_page_count spinlock. As explained earlier. Please add a motivation here. Feel free to reuse wording from http://lkml.kernel.org/r/20181107103630.GF2453@dhcp22.suse.cz > > Signed-off-by: Arun KS <arunks@codeaurora.org> > Reviewed-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru> > Acked-by: Michal Hocko <mhocko@suse.com> > Acked-by: Vlastimil Babka <vbabka@suse.cz> > --- > include/linux/mmzone.h | 6 ------ > mm/page_alloc.c | 5 ----- > 2 files changed, 11 deletions(-) > > diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h > index e73dc31..c71b4d9 100644 > --- a/include/linux/mmzone.h > +++ b/include/linux/mmzone.h > @@ -428,12 +428,6 @@ struct zone { > * Write access to present_pages at runtime should be protected by > * mem_hotplug_begin/end(). Any reader who can't tolerant drift of > * present_pages should get_online_mems() to get a stable value. > - * > - * Read access to managed_pages should be safe because it's unsigned > - * long. Write access to zone->managed_pages and totalram_pages are > - * protected by managed_page_count_lock at runtime. Idealy only > - * adjust_managed_page_count() should be used instead of directly > - * touching zone->managed_pages and totalram_pages. > */ > atomic_long_t managed_pages; > unsigned long spanned_pages; > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > index f8b64cc..26c5e14 100644 > --- a/mm/page_alloc.c > +++ b/mm/page_alloc.c > @@ -122,9 +122,6 @@ > }; > EXPORT_SYMBOL(node_states); > > -/* Protect totalram_pages and zone->managed_pages */ > -static DEFINE_SPINLOCK(managed_page_count_lock); > - > atomic_long_t _totalram_pages __read_mostly; > EXPORT_SYMBOL(_totalram_pages); > unsigned long totalreserve_pages __read_mostly; > @@ -7065,14 +7062,12 @@ static int __init cmdline_parse_movablecore(char *p) > > void adjust_managed_page_count(struct page *page, long count) > { > - spin_lock(&managed_page_count_lock); > atomic_long_add(count, &page_zone(page)->managed_pages); > totalram_pages_add(count); > #ifdef CONFIG_HIGHMEM > if (PageHighMem(page)) > totalhigh_pages_add(count); > #endif > - spin_unlock(&managed_page_count_lock); > } > EXPORT_SYMBOL(adjust_managed_page_count); > > -- > 1.9.1
On 2018-11-08 14:04, Michal Hocko wrote: > On Thu 08-11-18 13:53:18, Arun KS wrote: >> Now totalram_pages and managed_pages are atomic varibles. No need >> of managed_page_count spinlock. > > As explained earlier. Please add a motivation here. Feel free to reuse > wording from > http://lkml.kernel.org/r/20181107103630.GF2453@dhcp22.suse.cz Sure. Will add in next spin. Regards, Arun > >> >> Signed-off-by: Arun KS <arunks@codeaurora.org> >> Reviewed-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru> >> Acked-by: Michal Hocko <mhocko@suse.com> >> Acked-by: Vlastimil Babka <vbabka@suse.cz> >> --- >> include/linux/mmzone.h | 6 ------ >> mm/page_alloc.c | 5 ----- >> 2 files changed, 11 deletions(-) >> >> diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h >> index e73dc31..c71b4d9 100644 >> --- a/include/linux/mmzone.h >> +++ b/include/linux/mmzone.h >> @@ -428,12 +428,6 @@ struct zone { >> * Write access to present_pages at runtime should be protected by >> * mem_hotplug_begin/end(). Any reader who can't tolerant drift of >> * present_pages should get_online_mems() to get a stable value. >> - * >> - * Read access to managed_pages should be safe because it's unsigned >> - * long. Write access to zone->managed_pages and totalram_pages are >> - * protected by managed_page_count_lock at runtime. Idealy only >> - * adjust_managed_page_count() should be used instead of directly >> - * touching zone->managed_pages and totalram_pages. >> */ >> atomic_long_t managed_pages; >> unsigned long spanned_pages; >> diff --git a/mm/page_alloc.c b/mm/page_alloc.c >> index f8b64cc..26c5e14 100644 >> --- a/mm/page_alloc.c >> +++ b/mm/page_alloc.c >> @@ -122,9 +122,6 @@ >> }; >> EXPORT_SYMBOL(node_states); >> >> -/* Protect totalram_pages and zone->managed_pages */ >> -static DEFINE_SPINLOCK(managed_page_count_lock); >> - >> atomic_long_t _totalram_pages __read_mostly; >> EXPORT_SYMBOL(_totalram_pages); >> unsigned long totalreserve_pages __read_mostly; >> @@ -7065,14 +7062,12 @@ static int __init >> cmdline_parse_movablecore(char *p) >> >> void adjust_managed_page_count(struct page *page, long count) >> { >> - spin_lock(&managed_page_count_lock); >> atomic_long_add(count, &page_zone(page)->managed_pages); >> totalram_pages_add(count); >> #ifdef CONFIG_HIGHMEM >> if (PageHighMem(page)) >> totalhigh_pages_add(count); >> #endif >> - spin_unlock(&managed_page_count_lock); >> } >> EXPORT_SYMBOL(adjust_managed_page_count); >> >> -- >> 1.9.1
On Thu 08-11-18 15:33:06, Arun KS wrote: > On 2018-11-08 14:04, Michal Hocko wrote: > > On Thu 08-11-18 13:53:18, Arun KS wrote: > > > Now totalram_pages and managed_pages are atomic varibles. No need > > > of managed_page_count spinlock. > > > > As explained earlier. Please add a motivation here. Feel free to reuse > > wording from > > http://lkml.kernel.org/r/20181107103630.GF2453@dhcp22.suse.cz > > Sure. Will add in next spin. Andrew usually updates changelogs if you give him the full wording. I would wait few days before resubmitting, if that is needed at all. 0day will throw a lot of random configs which can reveal some leftovers.
On 2018-11-08 15:44, Michal Hocko wrote: > On Thu 08-11-18 15:33:06, Arun KS wrote: >> On 2018-11-08 14:04, Michal Hocko wrote: >> > On Thu 08-11-18 13:53:18, Arun KS wrote: >> > > Now totalram_pages and managed_pages are atomic varibles. No need >> > > of managed_page_count spinlock. >> > >> > As explained earlier. Please add a motivation here. Feel free to reuse >> > wording from >> > http://lkml.kernel.org/r/20181107103630.GF2453@dhcp22.suse.cz >> >> Sure. Will add in next spin. > > Andrew usually updates changelogs if you give him the full wording. > I would wait few days before resubmitting, if that is needed at all. mm: Remove managed_page_count spinlock Now that totalram_pages and managed_pages are atomic varibles, no need of managed_page_count spinlock. The lock had really a weak consistency guarantee. It hasn't been used for anything but the update but no reader actually cares about all the values being updated to be in sync. Signed-off-by: Arun KS <arunks@codeaurora.org> Reviewed-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> > 0day will throw a lot of random configs which can reveal some > leftovers. Yea. Fixed few of them during v3. Regards, Arun
On 2018-11-08 15:44, Michal Hocko wrote: > On Thu 08-11-18 15:33:06, Arun KS wrote: >> On 2018-11-08 14:04, Michal Hocko wrote: >> > On Thu 08-11-18 13:53:18, Arun KS wrote: >> > > Now totalram_pages and managed_pages are atomic varibles. No need >> > > of managed_page_count spinlock. >> > >> > As explained earlier. Please add a motivation here. Feel free to reuse >> > wording from >> > http://lkml.kernel.org/r/20181107103630.GF2453@dhcp22.suse.cz >> >> Sure. Will add in next spin. > > Andrew usually updates changelogs if you give him the full wording. > I would wait few days before resubmitting, if that is needed at all. > 0day will throw a lot of random configs which can reveal some > leftovers. 0day sent one more failure. Will fix that and resend one more version. Regards, Arun
diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h index e73dc31..c71b4d9 100644 --- a/include/linux/mmzone.h +++ b/include/linux/mmzone.h @@ -428,12 +428,6 @@ struct zone { * Write access to present_pages at runtime should be protected by * mem_hotplug_begin/end(). Any reader who can't tolerant drift of * present_pages should get_online_mems() to get a stable value. - * - * Read access to managed_pages should be safe because it's unsigned - * long. Write access to zone->managed_pages and totalram_pages are - * protected by managed_page_count_lock at runtime. Idealy only - * adjust_managed_page_count() should be used instead of directly - * touching zone->managed_pages and totalram_pages. */ atomic_long_t managed_pages; unsigned long spanned_pages; diff --git a/mm/page_alloc.c b/mm/page_alloc.c index f8b64cc..26c5e14 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -122,9 +122,6 @@ }; EXPORT_SYMBOL(node_states); -/* Protect totalram_pages and zone->managed_pages */ -static DEFINE_SPINLOCK(managed_page_count_lock); - atomic_long_t _totalram_pages __read_mostly; EXPORT_SYMBOL(_totalram_pages); unsigned long totalreserve_pages __read_mostly; @@ -7065,14 +7062,12 @@ static int __init cmdline_parse_movablecore(char *p) void adjust_managed_page_count(struct page *page, long count) { - spin_lock(&managed_page_count_lock); atomic_long_add(count, &page_zone(page)->managed_pages); totalram_pages_add(count); #ifdef CONFIG_HIGHMEM if (PageHighMem(page)) totalhigh_pages_add(count); #endif - spin_unlock(&managed_page_count_lock); } EXPORT_SYMBOL(adjust_managed_page_count);