[PATCH] overcommit symbolic constants

Andries.Brouwer_at_cwi.nl
Date: 09/30/04

  • Next message: Stephen Tweedie: "[Patch 1/10]: ext3 online resize: fix error codes" 
    Date:	Thu, 30 Sep 2004 15:41:27 +0200 (MEST)
To: akpm@osdl.org, torvalds@osdl.org

    Played a bit with overcommit the past hour.
    Am not entirely satisfied with the no overcommit mode 2 -
    programs segfault when the system is close to that boundary.
    So, instead of the somewhat larger patch that I planned to send,
    just symbolic names for the modes.

    Andries

    diff -uprN -X /linux/dontdiff a/arch/arm/mm/init.c b/arch/arm/mm/init.c
    --- a/arch/arm/mm/init.c 2004-08-26 22:05:07.000000000 +0200
    +++ b/arch/arm/mm/init.c 2004-09-30 15:34:51.000000000 +0200
    @@ -590,7 +590,7 @@ void __init mem_init(void)
                      * anywhere without overcommit, so turn
                      * it on by default.
                      */
    - sysctl_overcommit_memory = 1;
    + sysctl_overcommit_memory = OVERCOMMIT_ALWAYS;
             }
     }
     
    diff -uprN -X /linux/dontdiff a/arch/arm26/mm/init.c b/arch/arm26/mm/init.c
    --- a/arch/arm26/mm/init.c 2004-08-26 22:05:07.000000000 +0200
    +++ b/arch/arm26/mm/init.c 2004-09-30 15:34:51.000000000 +0200
    @@ -376,7 +376,7 @@ void __init mem_init(void)
              * Turn on overcommit on tiny machines
              */
             if (PAGE_SIZE >= 16384 && num_physpages <= 128) {
    - sysctl_overcommit_memory = 1;
    + sysctl_overcommit_memory = OVERCOMMIT_ALWAYS;
                     printk("Turning on overcommit\n");
             }
     }
    diff -uprN -X /linux/dontdiff a/Documentation/vm/overcommit-accounting b/Documentation/vm/overcommit-accounting
    --- a/Documentation/vm/overcommit-accounting 2003-12-18 03:58:28.000000000 +0100
    +++ b/Documentation/vm/overcommit-accounting 2004-09-30 15:34:51.000000000 +0200
    @@ -1,4 +1,4 @@
    -The Linux kernel supports three overcommit handling modes
    +The Linux kernel supports the following overcommit handling modes
     
     0 - Heuristic overcommit handling. Obvious overcommits of
                     address space are refused. Used for a typical system. It
    @@ -7,10 +7,10 @@ The Linux kernel supports three overcomm
                     allocate slighly more memory in this mode. This is the
                     default.
     
    -1 - No overcommit handling. Appropriate for some scientific
    +1 - Always overcommit. Appropriate for some scientific
                     applications.
     
    -2 - (NEW) strict overcommit. The total address space commit
    +2 - Don't overcommit. The total address space commit
                     for the system is not permitted to exceed swap + a
                     configurable percentage (default is 50) of physical RAM.
                     Depending on the percentage you use, in most situations
    @@ -27,7 +27,7 @@ Gotchas
     
     The C language stack growth does an implicit mremap. If you want absolute
     guarantees and run close to the edge you MUST mmap your stack for the
    -largest size you think you will need. For typical stack usage is does
    +largest size you think you will need. For typical stack usage this does
     not matter much but it's a corner case if you really really care
     
     In mode 2 the MAP_NORESERVE flag is ignored.
    diff -uprN -X /linux/dontdiff a/include/linux/mman.h b/include/linux/mman.h
    --- a/include/linux/mman.h 2003-12-18 03:58:15.000000000 +0100
    +++ b/include/linux/mman.h 2004-09-30 15:34:51.000000000 +0200
    @@ -10,6 +10,9 @@
     #define MREMAP_MAYMOVE 1
     #define MREMAP_FIXED 2
     
    +#define OVERCOMMIT_GUESS 0
    +#define OVERCOMMIT_ALWAYS 1
    +#define OVERCOMMIT_NEVER 2
     extern int sysctl_overcommit_memory;
     extern int sysctl_overcommit_ratio;
     extern atomic_t vm_committed_space;
    diff -uprN -X /linux/dontdiff a/mm/mmap.c b/mm/mmap.c
    --- a/mm/mmap.c 2004-08-26 22:05:44.000000000 +0200
    +++ b/mm/mmap.c 2004-09-30 15:35:27.000000000 +0200
    @@ -54,7 +54,7 @@ pgprot_t protection_map[16] = {
             __S000, __S001, __S010, __S011, __S100, __S101, __S110, __S111
     };
     
    -int sysctl_overcommit_memory = 0; /* default is heuristic overcommit */
    +int sysctl_overcommit_memory = OVERCOMMIT_GUESS; /* heuristic overcommit */
     int sysctl_overcommit_ratio = 50; /* default is 50% */
     int sysctl_max_map_count = DEFAULT_MAX_MAP_COUNT;
     atomic_t vm_committed_space = ATOMIC_INIT(0);
    @@ -882,7 +882,7 @@ munmap_back:
                     return -ENOMEM;
     
             if (accountable && (!(flags & MAP_NORESERVE) ||
    - sysctl_overcommit_memory > 1)) {
    + sysctl_overcommit_memory == OVERCOMMIT_NEVER)) {
                     if (vm_flags & VM_SHARED) {
                             /* Check memory availability in shmem_file_setup? */
                             vm_flags |= VM_ACCOUNT;
    diff -uprN -X /linux/dontdiff a/mm/nommu.c b/mm/nommu.c
    --- a/mm/nommu.c 2004-08-26 22:05:44.000000000 +0200
    +++ b/mm/nommu.c 2004-09-30 15:34:51.000000000 +0200
    @@ -30,7 +30,7 @@ unsigned long max_mapnr;
     unsigned long num_physpages;
     unsigned long askedalloc, realalloc;
     atomic_t vm_committed_space = ATOMIC_INIT(0);
    -int sysctl_overcommit_memory; /* default is heuristic overcommit */
    +int sysctl_overcommit_memory = OVERCOMMIT_GUESS; /* heuristic overcommit */
     int sysctl_overcommit_ratio = 50; /* default is 50% */
     
     int sysctl_max_map_count = DEFAULT_MAX_MAP_COUNT;
    diff -uprN -X /linux/dontdiff a/security/commoncap.c b/security/commoncap.c
    --- a/security/commoncap.c 2004-06-24 17:11:21.000000000 +0200
    +++ b/security/commoncap.c 2004-09-30 15:34:51.000000000 +0200
    @@ -314,10 +314,10 @@ int cap_vm_enough_memory(long pages)
             /*
              * Sometimes we want to use more memory than we have
              */
    - if (sysctl_overcommit_memory == 1)
    + if (sysctl_overcommit_memory == OVERCOMMIT_ALWAYS)
                     return 0;
     
    - if (sysctl_overcommit_memory == 0) {
    + if (sysctl_overcommit_memory == OVERCOMMIT_GUESS) {
                     unsigned long n;
     
                     free = get_page_cache_size();
    diff -uprN -X /linux/dontdiff a/security/dummy.c b/security/dummy.c
    --- a/security/dummy.c 2004-08-26 22:05:50.000000000 +0200
    +++ b/security/dummy.c 2004-09-30 15:34:51.000000000 +0200
    @@ -121,10 +121,10 @@ static int dummy_vm_enough_memory(long p
             /*
              * Sometimes we want to use more memory than we have
              */
    - if (sysctl_overcommit_memory == 1)
    + if (sysctl_overcommit_memory == OVERCOMMIT_ALWAYS)
                     return 0;
     
    - if (sysctl_overcommit_memory == 0) {
    + if (sysctl_overcommit_memory == OVERCOMMIT_GUESS) {
                     free = get_page_cache_size();
                     free += nr_free_pages();
                     free += nr_swap_pages;
    diff -uprN -X /linux/dontdiff a/security/selinux/hooks.c b/security/selinux/hooks.c
    --- a/security/selinux/hooks.c 2004-08-26 22:05:50.000000000 +0200
    +++ b/security/selinux/hooks.c 2004-09-30 15:34:51.000000000 +0200
    @@ -1548,10 +1548,10 @@ static int selinux_vm_enough_memory(long
             /*
              * Sometimes we want to use more memory than we have
              */
    - if (sysctl_overcommit_memory == 1)
    + if (sysctl_overcommit_memory == OVERCOMMIT_ALWAYS)
                     return 0;
     
    - if (sysctl_overcommit_memory == 0) {
    + if (sysctl_overcommit_memory == OVERCOMMIT_GUESS) {
                     free = get_page_cache_size();
                     free += nr_free_pages();
                     free += nr_swap_pages;
    -
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  • Next message: Stephen Tweedie: "[Patch 1/10]: ext3 online resize: fix error codes"