lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
Open Source and information security mailing list archives
| ||
|
Date: Tue, 11 Jun 2019 12:10:36 +0000 From: "Chengang (L)" <cg.chen@...wei.com> To: Wei Yang <richard.weiyang@...il.com> CC: "akpm@...ux-foundation.org" <akpm@...ux-foundation.org>, "mhocko@...e.com" <mhocko@...e.com>, "vbabka@...e.cz" <vbabka@...e.cz>, "osalvador@...e.de" <osalvador@...e.de>, "pavel.tatashin@...rosoft.com" <pavel.tatashin@...rosoft.com>, "mgorman@...hsingularity.net" <mgorman@...hsingularity.net>, "rppt@...ux.ibm.com" <rppt@...ux.ibm.com>, "alexander.h.duyck@...ux.intel.com" <alexander.h.duyck@...ux.intel.com>, "linux-mm@...ck.org" <linux-mm@...ck.org>, "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org> Subject: Re: [PATCH] mm: align up min_free_kbytes to multipy of 4 Hi Wei Yang >On Sun, Jun 09, 2019 at 05:10:28PM +0800, ChenGang wrote: >>Usually the value of min_free_kbytes is multiply of 4, and in this case >>,the right shift is ok. >>But if it's not, the right-shifting operation will lose the low 2 bits, >But PAGE_SHIFT is not always 12. You are right, and this is not the key point, this is just an example. >>and this cause kernel don't reserve enough memory. >>So it's necessary to align the value of min_free_kbytes to multiply of 4. >>For example, if min_free_kbytes is 64, then should keep 16 pages, but >>if min_free_kbytes is 65 or 66, then should keep 17 pages. >> >>Signed-off-by: ChenGang <cg.chen@...wei.com> >>--- >> mm/page_alloc.c | 3 ++- >> 1 file changed, 2 insertions(+), 1 deletion(-) >> >>diff --git a/mm/page_alloc.c b/mm/page_alloc.c index d66bc8a..1baeeba >>100644 >>--- a/mm/page_alloc.c >>+++ b/mm/page_alloc.c >>@@ -7611,7 +7611,8 @@ static void setup_per_zone_lowmem_reserve(void) >> >> static void __setup_per_zone_wmarks(void) { >>- unsigned long pages_min = min_free_kbytes >> (PAGE_SHIFT - 10); >>+ unsigned long pages_min = >>+ (PAGE_ALIGN(min_free_kbytes * 1024) / 1024) >> (PAGE_SHIFT - 10); >In my mind, pages_min is an estimated value. Do we need to be so precise? This is the key point, user can set this value through interface/proc/sys/vm/min_free_kbytes, so a bit more precise is better. >> unsigned long lowmem_pages = 0; >> struct zone *zone; >> unsigned long flags; >>-- >>1.8.5.6 >-- >Wei Yang >Help you, Help me
Powered by blists - more mailing lists