| 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
| ||
|
Message-ID: <512FF35B.2030200@gmail.com>
Date: Fri, 01 Mar 2013 08:16:27 +0800
From: Simon Jeons <simon.jeons@...il.com>
To: Andrew Shewmaker <agshew@...il.com>
CC: Andrew Morton <akpm@...ux-foundation.org>, linux-mm@...ck.org,
linux-kernel@...r.kernel.org
Subject: Re: [RFC PATCH v2 2/2] mm: tuning hardcoded reserved memory
On 02/28/2013 05:09 AM, Andrew Shewmaker wrote:
> Add a rootuser_reserve_pages knob to allow admins of large memory
> systems running with overcommit disabled to change the hardcoded
> memory reserve to something other than 3%.
>
> Signed-off-by: Andrew Shewmaker <agshew@...il.com>
>
> ---
>
> Patch based off of mmotm git tree as of February 27th.
>
> I set rootuser_reserve pages to be a default of 1000, and I suppose
> I should have initialzed similarly to the way min_free_kbytes is,
> scaling it with the size of the box. However, I wanted to get a
> simple version of this patch out for feedback to see if it has any
> chance of acceptance or if I need to take an entirely different
> approach.
>
> Any feedback will be appreciated!
>
> Documentation/sysctl/vm.txt | 9 +++++++++
> include/linux/mm.h | 2 ++
> kernel/sysctl.c | 8 ++++++++
> mm/mmap.c | 30 +++++++++++++++++++++++-------
> 4 files changed, 42 insertions(+), 7 deletions(-)
>
> diff --git a/Documentation/sysctl/vm.txt b/Documentation/sysctl/vm.txt
> index 078701f..3a71de9 100644
> --- a/Documentation/sysctl/vm.txt
> +++ b/Documentation/sysctl/vm.txt
> @@ -51,6 +51,7 @@ Currently, these files are in /proc/sys/vm:
> - page-cluster
> - panic_on_oom
> - percpu_pagelist_fraction
> +- rootuser_reserve_pages
> - stat_interval
> - swappiness
> - vfs_cache_pressure
> @@ -628,6 +629,14 @@ the high water marks for each per cpu page list.
>
> ==============================================================
>
> +rootuser_reserve_pages
> +
> +The number of free pages left in the system that should be reserved for users
> +with the capability cap_sys_admin. The default falue is 3% of total system
s/falue/value
> +memory. Changing this takes effect whenever an application requests memory.
> +
> +==============================================================
> +
> stat_interval
>
> The time interval between which vm statistics are updated. The default
> diff --git a/include/linux/mm.h b/include/linux/mm.h
> index 66e2f7c..af7b39f 100644
> --- a/include/linux/mm.h
> +++ b/include/linux/mm.h
> @@ -1677,6 +1677,8 @@ int in_gate_area_no_mm(unsigned long addr);
>
> int drop_caches_sysctl_handler(struct ctl_table *, int,
> void __user *, size_t *, loff_t *);
> +int rootuser_reserve_pages_sysctl_handler(struct ctl_table *, int,
> + void __user *, size_t *, loff_t *);
> unsigned long shrink_slab(struct shrink_control *shrink,
> unsigned long nr_pages_scanned,
> unsigned long lru_pages);
> diff --git a/kernel/sysctl.c b/kernel/sysctl.c
> index c88878d..cd1987e 100644
> --- a/kernel/sysctl.c
> +++ b/kernel/sysctl.c
> @@ -96,6 +96,7 @@
> /* External variables not in a header file. */
> extern int sysctl_overcommit_memory;
> extern int sysctl_overcommit_ratio;
> +extern int sysctl_rootuser_reserve_pages;
> extern int max_threads;
> extern int suid_dumpable;
> #ifdef CONFIG_COREDUMP
> @@ -1413,6 +1414,13 @@ static struct ctl_table vm_table[] = {
> .extra2 = &one,
> },
> #endif
> + {
> + .procname = "rootuser_reserve_pages",
> + .data = &sysctl_rootuser_reserve_pages,
> + .maxlen = sizeof(sysctl_rootuser_reserve_pages),
> + .mode = 0644,
> + .proc_handler = rootuser_reserve_pages_sysctl_handler,
> + },
> { }
> };
>
> diff --git a/mm/mmap.c b/mm/mmap.c
> index d1e4124..b58af97 100644
> --- a/mm/mmap.c
> +++ b/mm/mmap.c
> @@ -32,6 +32,7 @@
> #include <linux/khugepaged.h>
> #include <linux/uprobes.h>
> #include <linux/rbtree_augmented.h>
> +#include <linux/sysctl.h>
>
> #include <asm/uaccess.h>
> #include <asm/cacheflush.h>
> @@ -83,6 +84,7 @@ EXPORT_SYMBOL(vm_get_page_prot);
> int sysctl_overcommit_memory __read_mostly = OVERCOMMIT_GUESS; /* heuristic overcommit */
> int sysctl_overcommit_ratio __read_mostly = 50; /* default is 50% */
> int sysctl_max_map_count __read_mostly = DEFAULT_MAX_MAP_COUNT;
> +int sysctl_rootuser_reserve_pages __read_mostly = 1000;
> /*
> * Make sure vm_committed_as in one cacheline and not cacheline shared with
> * other variables. It can be updated by several CPUs frequently.
> @@ -165,7 +167,7 @@ int __vm_enough_memory(struct mm_struct *mm, long pages, int cap_sys_admin)
> * Leave the last 3% for root
> */
> if (!cap_sys_admin)
> - free -= free / 32;
> + free -= sysctl_rootuser_reserve_pages;
>
> if (free > pages)
> return 0;
> @@ -179,9 +181,9 @@ int __vm_enough_memory(struct mm_struct *mm, long pages, int cap_sys_admin)
> * Leave the last 3% for root
> */
> if (!cap_sys_admin)
> - allowed -= allowed / 32;
> + allowed -= sysctl_rootuser_reserve_pages;
> allowed += total_swap_pages;
>
> if (percpu_counter_read_positive(&vm_committed_as) < allowed)
> return 0;
> error:
> @@ -3052,3 +3049,22 @@ void __init mmap_init(void)
> ret = percpu_counter_init(&vm_committed_as, 0);
> VM_BUG_ON(ret);
> }
> +
> +/*
> + * rootuser_reserve_pages_sysctl_handler - just a wrapper around proc_dointvec_minmax() so
> + * that we can cap the number of pages to the current number of free pages.
> + */
> +int rootuser_reserve_pages_sysctl_handler(ctl_table *table, int write,
> + void __user *buffer, size_t *length, loff_t *ppos)
> +{
> + unsigned long free;
> +
> + proc_dointvec(table, write, buffer, length, ppos);
> +
> + if (write) {
> + free = global_page_state(NR_FREE_PAGES);
> + if (sysctl_rootuser_reserve_pages > free)
> + sysctl_rootuser_reserve_pages = free;
> + }
> + return 0;
> +}
>
> --
> To unsubscribe, send a message with 'unsubscribe linux-mm' in
> the body to majordomo@...ck.org. For more info on Linux MM,
> see: http://www.linux-mm.org/ .
> Don't email: <a href=mailto:"dont@...ck.org"> email@...ck.org </a>
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
Powered by blists - more mailing lists