On 07/05/2013 12:20 AM, Michal Hocko wrote: [snip]
> --- > From 5f089c0b2a57ff6c08710ac9698d65aede06079f Mon Sep 17 00:00:00 2001 > From: Michal Hocko <[email protected]> > Date: Thu, 4 Jul 2013 17:15:54 +0200 > Subject: [PATCH] mm: Honor min_free_kbytes set by user > > min_free_kbytes is updated during memory hotplug (by init_per_zone_wmark_min) > currently which is right thing to do in most cases but this could be > unexpected if admin increased the value to prevent from allocation > failures and the new min_free_kbytes would be decreased as a result of > memory hotadd. > > This patch saves the user defined value and allows updating > min_free_kbytes only if it is higher than the saved one. > > A warning is printed when the new value is ignored. Looks reasonable. Acked-by: Zhang Yanfei <[email protected]> > > Signed-off-by: Michal Hocko <[email protected]> > --- > mm/page_alloc.c | 24 +++++++++++++++++------- > 1 file changed, 17 insertions(+), 7 deletions(-) > > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > index 22c528e..9c011fc 100644 > --- a/mm/page_alloc.c > +++ b/mm/page_alloc.c > @@ -204,6 +204,7 @@ static char * const zone_names[MAX_NR_ZONES] = { > }; > > int min_free_kbytes = 1024; > +int user_min_free_kbytes; > > static unsigned long __meminitdata nr_kernel_pages; > static unsigned long __meminitdata nr_all_pages; > @@ -5592,14 +5593,21 @@ static void __meminit > setup_per_zone_inactive_ratio(void) > int __meminit init_per_zone_wmark_min(void) > { > unsigned long lowmem_kbytes; > + int new_min_free_kbytes; > > lowmem_kbytes = nr_free_buffer_pages() * (PAGE_SIZE >> 10); > - > - min_free_kbytes = int_sqrt(lowmem_kbytes * 16); > - if (min_free_kbytes < 128) > - min_free_kbytes = 128; > - if (min_free_kbytes > 65536) > - min_free_kbytes = 65536; > + new_min_free_kbytes = int_sqrt(lowmem_kbytes * 16); > + > + if (new_min_free_kbytes > user_min_free_kbytes) { > + min_free_kbytes = new_min_free_kbytes; > + if (min_free_kbytes < 128) > + min_free_kbytes = 128; > + if (min_free_kbytes > 65536) > + min_free_kbytes = 65536; > + } else { > + pr_warn("min_free_kbytes is not updated to %d because user > defined value %d is preferred\n", > + new_min_free_kbytes, user_min_free_kbytes); > + } > setup_per_zone_wmarks(); > refresh_zone_stat_thresholds(); > setup_per_zone_lowmem_reserve(); > @@ -5617,8 +5625,10 @@ int min_free_kbytes_sysctl_handler(ctl_table *table, > int write, > void __user *buffer, size_t *length, loff_t *ppos) > { > proc_dointvec(table, write, buffer, length, ppos); > - if (write) > + if (write) { > + user_min_free_kbytes = min_free_kbytes; > setup_per_zone_wmarks(); > + } > return 0; > } > -- Thanks. Zhang Yanfei -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
