* zhouzihan30 <15645113830zzh@xxxxxxxxx> [241213 03:17]: The subject of this patch is really poor. "some memory information"? considering the text below is so much more descriptive, could we have a meaningful subject? You will not get the proper people looking at this without a decent subject. At least make it "mm/page_alloc" ? > In the kernel, the zone's lowmem_reserve and _watermark, and the global > variable 'totalreserve_pages' depend on the value of managed_pages, > but after running adjust_managed_page_count, these values didn't updated, > which caused some problems. > > For example, in a system with six 1GB large pages, we found that the value > of protection in zoneinfo (zone->lowmem_reserve), is not right. > Its value seems calculated from the initial managed_pages, > but after the managed_pages changed, was not updated. Only after reading > the file /proc/sys/vm/lowmem_reserve_ratio, updates happen. > > read file /proc/sys/vm/lowmem_reserve_ratio: > > lowmem_reserve_ratio_sysctl_handler > ----setup_per_zone_lowmem_reserve > --------calculate_totalreserve_pages > > protection changed after reading file: > > [root@test ~]# cat /proc/zoneinfo | grep protection > protection: (0, 2719, 57360, 0) > protection: (0, 0, 54640, 0) > protection: (0, 0, 0, 0) > protection: (0, 0, 0, 0) > [root@test ~]# cat /proc/sys/vm/lowmem_reserve_ratio > 256 256 32 0 > [root@test ~]# cat /proc/zoneinfo | grep protection > protection: (0, 2735, 63524, 0) > protection: (0, 0, 60788, 0) > protection: (0, 0, 0, 0) > protection: (0, 0, 0, 0) > > lowmem_reserve increased also makes the totalreserve_pages increased, > which causes a decrease in available memory. The one above is just a > test machine, and the increase is not significant. On our online machine, > the reserved memory will increase by several GB due to reading this file. > It is clearly unreasonable to cause a sharp drop in available memory just > by reading a file. > > In this patch, we update reserve memory when update managed_pages, The > size of reserved memory becomes stable. But it seems that the _watermark > should also be updated along with the managed_pages. We have not done > it because we are unsure if it is reasonable to set the watermark through > the initial managed_pages. If it is not reasonable, we will propose > new patch. > > Signed-off-by: zhouzihan30 <zhouzihan30@xxxxxx> > Signed-off-by: yaowenchao1 <yaowenchao@xxxxxx> Who are these people, really? https://www.kernel.org/doc/html/v6.12/process/submitting-patches.html#sign-your-work-the-developer-s-certificate-of-origin Also, the Signed-off-by doesn't match the sending email (gmail vs jd.com)? > --- > mm/page_alloc.c | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > index b6958333054d..b23e128afbcd 100644 > --- a/mm/page_alloc.c > +++ b/mm/page_alloc.c > @@ -5826,10 +5826,13 @@ __meminit void zone_pcp_init(struct zone *zone) > zone->present_pages, zone_batchsize(zone)); > } > > +static void setup_per_zone_lowmem_reserve(void); > + > void adjust_managed_page_count(struct page *page, long count) > { > atomic_long_add(count, &page_zone(page)->managed_pages); > totalram_pages_add(count); > + setup_per_zone_lowmem_reserve(); > } > EXPORT_SYMBOL(adjust_managed_page_count); > > -- > 2.33.0 > >
