From f8ade3666c8612c33929f499b3c8800d83f43d84 Mon Sep 17 00:00:00 2001 From: Rik van Riel Date: Thu, 1 Sep 2011 15:26:50 -0400 Subject: add extra free kbytes tunable Add a userspace visible knob to tell the VM to keep an extra amount of memory free, by increasing the gap between each zone's min and low watermarks. This is useful for realtime applications that call system calls and have a bound on the number of allocations that happen in any short time period. In this application, extra_free_kbytes would be left at an amount equal to or larger than than the maximum number of allocations that happen in any burst. It may also be useful to reduce the memory use of virtual machines (temporarily?), in a way that does not cause memory fragmentation like ballooning does. [ccross] Revived for use on old kernels where no other solution exists. The tunable will be removed on kernels that do better at avoiding direct reclaim. Change-Id: I765a42be8e964bfd3e2886d1ca85a29d60c3bb3e Signed-off-by: Rik van Riel Signed-off-by: Colin Cross --- kernel/sysctl.c | 9 +++++++++ 1 file changed, 9 insertions(+) (limited to 'kernel/sysctl.c') diff --git a/kernel/sysctl.c b/kernel/sysctl.c index dc6858d6639e..81fe3bde9fee 100644 --- a/kernel/sysctl.c +++ b/kernel/sysctl.c @@ -104,6 +104,7 @@ extern char core_pattern[]; extern unsigned int core_pipe_limit; #endif extern int pid_max; +extern int extra_free_kbytes; extern int pid_max_min, pid_max_max; extern int percpu_pagelist_fraction; extern int compat_log; @@ -1392,6 +1393,14 @@ static struct ctl_table vm_table[] = { .proc_handler = min_free_kbytes_sysctl_handler, .extra1 = &zero, }, + { + .procname = "extra_free_kbytes", + .data = &extra_free_kbytes, + .maxlen = sizeof(extra_free_kbytes), + .mode = 0644, + .proc_handler = min_free_kbytes_sysctl_handler, + .extra1 = &zero, + }, { .procname = "percpu_pagelist_fraction", .data = &percpu_pagelist_fraction, -- cgit v1.2.3 From d49d88766ba924b3df96d9fc1c1a257b90970b74 Mon Sep 17 00:00:00 2001 From: dcashman Date: Tue, 12 Jan 2016 09:18:57 -0800 Subject: FROMLIST: mm: mmap: Add new /proc tunable for mmap_base ASLR. (cherry picked from commit https://lkml.org/lkml/2015/12/21/337) ASLR only uses as few as 8 bits to generate the random offset for the mmap base address on 32 bit architectures. This value was chosen to prevent a poorly chosen value from dividing the address space in such a way as to prevent large allocations. This may not be an issue on all platforms. Allow the specification of a minimum number of bits so that platforms desiring greater ASLR protection may determine where to place the trade-off. Bug: 24047224 Signed-off-by: Daniel Cashman Signed-off-by: Daniel Cashman Change-Id: Ibf9ed3d4390e9686f5cc34f605d509a20d40e6c2 --- kernel/sysctl.c | 22 ++++++++++++++++++++++ 1 file changed, 22 insertions(+) (limited to 'kernel/sysctl.c') diff --git a/kernel/sysctl.c b/kernel/sysctl.c index 81fe3bde9fee..35bfe0c1360b 100644 --- a/kernel/sysctl.c +++ b/kernel/sysctl.c @@ -1577,6 +1577,28 @@ static struct ctl_table vm_table[] = { .mode = 0644, .proc_handler = proc_doulongvec_minmax, }, +#ifdef CONFIG_HAVE_ARCH_MMAP_RND_BITS + { + .procname = "mmap_rnd_bits", + .data = &mmap_rnd_bits, + .maxlen = sizeof(mmap_rnd_bits), + .mode = 0600, + .proc_handler = proc_dointvec_minmax, + .extra1 = (void *)&mmap_rnd_bits_min, + .extra2 = (void *)&mmap_rnd_bits_max, + }, +#endif +#ifdef CONFIG_HAVE_ARCH_MMAP_RND_COMPAT_BITS + { + .procname = "mmap_rnd_compat_bits", + .data = &mmap_rnd_compat_bits, + .maxlen = sizeof(mmap_rnd_compat_bits), + .mode = 0600, + .proc_handler = proc_dointvec_minmax, + .extra1 = (void *)&mmap_rnd_compat_bits_min, + .extra2 = (void *)&mmap_rnd_compat_bits_max, + }, +#endif { } }; -- cgit v1.2.3