Messages in this thread | | | Subject | Re: [PATCH v4 2/4] mm/page_reporting: Export reporting order as module parameter | From | Gavin Shan <> | Date | Fri, 25 Jun 2021 16:08:13 +1000 |
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On 6/25/21 3:53 PM, Michael S. Tsirkin wrote: > On Fri, Jun 25, 2021 at 09:47:08AM +0800, Gavin Shan wrote: >> The macro PAGE_REPORTING_MIN_ORDER is defined as the page reporting >> threshold. It can't be adjusted at runtime. >> >> This introduces a variable (@page_reporting_order) to replace the >> marcro (PAGE_REPORTING_MIN_ORDER). MAX_ORDER is assigned to it initially, >> meaning the page reporting is disabled. It will be specified by driver >> if valid one is provided. Otherwise, it will fall back to @pageblock_order. >> It's also exported so that the page reporting order can be adjusted at >> runtime. >> >> Suggested-by: David Hildenbrand <david@redhat.com> >> Signed-off-by: Gavin Shan <gshan@redhat.com> >> Reviewed-by: Alexander Duyck <alexanderduyck@fb.com> >> --- >> Documentation/admin-guide/kernel-parameters.txt | 6 ++++++ >> mm/page_reporting.c | 9 +++++++-- >> mm/page_reporting.h | 5 ++--- >> 3 files changed, 15 insertions(+), 5 deletions(-) >> >> diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt >> index cb89dbdedc46..566c4b9af3cd 100644 >> --- a/Documentation/admin-guide/kernel-parameters.txt >> +++ b/Documentation/admin-guide/kernel-parameters.txt >> @@ -3566,6 +3566,12 @@ >> off: turn off poisoning (default) >> on: turn on poisoning >> >> + page_reporting.page_reporting_order= >> + [KNL] Minimal page reporting order >> + Format: <integer> >> + Adjust the minimal page reporting order. The page >> + reporting is disabled when it exceeds (MAX_ORDER-1). > > Which the admin knows how? Run grep in the kernel source? >
Well, I guess it's fine as it's used for debugging purpose. I guess it's mostly used by developers. Also, the value can be changed by the module parameter in "/sys/module/page_reporting" either.
>> + >> panic= [KNL] Kernel behaviour on panic: delay <timeout> >> timeout > 0: seconds before rebooting >> timeout = 0: wait forever >> diff --git a/mm/page_reporting.c b/mm/page_reporting.c >> index df9c5054e1b4..34bf4d26c2c4 100644 >> --- a/mm/page_reporting.c >> +++ b/mm/page_reporting.c >> @@ -4,12 +4,17 @@ >> #include <linux/page_reporting.h> >> #include <linux/gfp.h> >> #include <linux/export.h> >> +#include <linux/module.h> >> #include <linux/delay.h> >> #include <linux/scatterlist.h> >> >> #include "page_reporting.h" >> #include "internal.h" >> >> +unsigned int page_reporting_order = MAX_ORDER; >> +module_param(page_reporting_order, uint, 0644); >> +MODULE_PARM_DESC(page_reporting_order, "Set page reporting order"); >> + >> #define PAGE_REPORTING_DELAY (2 * HZ) >> static struct page_reporting_dev_info __rcu *pr_dev_info __read_mostly; >> >> @@ -229,7 +234,7 @@ page_reporting_process_zone(struct page_reporting_dev_info *prdev, >> >> /* Generate minimum watermark to be able to guarantee progress */ >> watermark = low_wmark_pages(zone) + >> - (PAGE_REPORTING_CAPACITY << PAGE_REPORTING_MIN_ORDER); >> + (PAGE_REPORTING_CAPACITY << page_reporting_order); > > > Looks like this makes it easy to trigger undefined behaviour. Just use > any value > 31. >
This function won't be run if page_reporting_order is more than (MAX_ORDER-1).
>> >> /* >> * Cancel request if insufficient free memory or if we failed >> @@ -239,7 +244,7 @@ page_reporting_process_zone(struct page_reporting_dev_info *prdev, >> return err; >> >> /* Process each free list starting from lowest order/mt */ >> - for (order = PAGE_REPORTING_MIN_ORDER; order < MAX_ORDER; order++) { >> + for (order = page_reporting_order; order < MAX_ORDER; order++) { >> for (mt = 0; mt < MIGRATE_TYPES; mt++) { >> /* We do not pull pages from the isolate free list */ >> if (is_migrate_isolate(mt)) >> diff --git a/mm/page_reporting.h b/mm/page_reporting.h >> index 2c385dd4ddbd..c51dbc228b94 100644 >> --- a/mm/page_reporting.h >> +++ b/mm/page_reporting.h >> @@ -10,10 +10,9 @@ >> #include <linux/pgtable.h> >> #include <linux/scatterlist.h> >> >> -#define PAGE_REPORTING_MIN_ORDER pageblock_order >> - >> #ifdef CONFIG_PAGE_REPORTING >> DECLARE_STATIC_KEY_FALSE(page_reporting_enabled); >> +extern unsigned int page_reporting_order; >> void __page_reporting_notify(void); >> >> static inline bool page_reported(struct page *page) >> @@ -38,7 +37,7 @@ static inline void page_reporting_notify_free(unsigned int order) >> return; >> >> /* Determine if we have crossed reporting threshold */ >> - if (order < PAGE_REPORTING_MIN_ORDER) >> + if (order < page_reporting_order) >> return; >> >> /* This will add a few cycles, but should be called infrequently */ >> -- >> 2.23.0 >
Thanks, Gavin
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