Messages in this thread Patch in this message | | | Date | Fri, 17 Sep 2004 15:18:30 +0200 | From | Utz Lehmann <> | Subject | Re: [PATCH] flexmmap: optimise mmap_base gap for hard limited stack |
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Ulrich Drepper [drepper@redhat.com] wrote: > > A check for CAP_SYS_RESOURCE can be added. But i dont think it's worth. > > It is needed. Otherwise how do you allow increasing the stack size > again once it has been limited? I've no problem with using the smallest > reserved stack region with !CAP_SYS_RESOURCE, but otherwise the existing > method should be used.
I made that change. The following patch only reduce the gap when the application can not extend the stack space anyway (hard limited stack && !CAP_SYS_RESOURCE). All other cases stay unchanged except for the 1 MB hole for soft limited stacks >128 MB.
It gave a nice way for making most of the default 128 MB gap usable for applications. Just run them with a hard stack limit.
Now i can allocate more than 3.8GiB in one chunk on x86 (this patch + exec-shield + 4g/4g + ulimit -H -s 8192).
Signed-off-by: Utz Lehmann <lkml@de.tecosim.com>
diff -Nrup linux-2.6.9-rc2/arch/i386/mm/mmap.c linux-2.6.9-rc2-gap4/arch/i386/mm/mmap.c --- linux-2.6.9-rc2/arch/i386/mm/mmap.c 2004-09-16 11:18:15.363366420 +0200 +++ linux-2.6.9-rc2-gap4/arch/i386/mm/mmap.c 2004-09-17 12:14:16.734968291 +0200 @@ -30,10 +30,13 @@ /* * Top of mmap area (just below the process stack). * - * Leave an at least ~128 MB hole. + * Leave an at least 1 MB hole between stack and mmap_base. + * Leave an at least 128 MB gap between TASK_SIZE and mmap_base with a + * soft rlimit stack. */ -#define MIN_GAP (128*1024*1024) -#define MAX_GAP (TASK_SIZE/6*5) +#define MIN_HOLE (1*1024*1024) +#define MIN_GAP (128*1024*1024 - MIN_HOLE) +#define MAX_GAP (TASK_SIZE/6*5 - MIN_HOLE) static inline unsigned long mmap_base(struct mm_struct *mm) { @@ -43,8 +46,11 @@ static inline unsigned long mmap_base(st gap = MIN_GAP; else if (gap > MAX_GAP) gap = MAX_GAP; + if ((gap > current->rlim[RLIMIT_STACK].rlim_max) && + !capable(CAP_SYS_RESOURCE)) + gap = current->rlim[RLIMIT_STACK].rlim_max; - return TASK_SIZE - (gap & PAGE_MASK); + return TASK_SIZE - ((gap + MIN_HOLE) & PAGE_MASK); } /* diff -Nrup linux-2.6.9-rc2/arch/ppc64/mm/mmap.c linux-2.6.9-rc2-gap4/arch/ppc64/mm/mmap.c --- linux-2.6.9-rc2/arch/ppc64/mm/mmap.c 2004-09-16 11:18:19.760799910 +0200 +++ linux-2.6.9-rc2-gap4/arch/ppc64/mm/mmap.c 2004-09-17 12:15:05.572696938 +0200 @@ -30,10 +30,13 @@ /* * Top of mmap area (just below the process stack). * - * Leave an at least ~128 MB hole. + * Leave an at least 1 MB hole between stack and mmap_base. + * Leave an at least 128 MB gap between TASK_SIZE and mmap_base with a + * soft rlimit stack. */ -#define MIN_GAP (128*1024*1024) -#define MAX_GAP (TASK_SIZE/6*5) +#define MIN_HOLE (1*1024*1024) +#define MIN_GAP (128*1024*1024 - MIN_HOLE) +#define MAX_GAP (TASK_SIZE/6*5 - MIN_HOLE) static inline unsigned long mmap_base(void) { @@ -43,8 +46,11 @@ static inline unsigned long mmap_base(vo gap = MIN_GAP; else if (gap > MAX_GAP) gap = MAX_GAP; + if ((gap > current->rlim[RLIMIT_STACK].rlim_max) && + !capable(CAP_SYS_RESOURCE)) + gap = current->rlim[RLIMIT_STACK].rlim_max; - return TASK_SIZE - (gap & PAGE_MASK); + return TASK_SIZE - ((gap + MIN_HOLE) & PAGE_MASK); } static inline int mmap_is_legacy(void) diff -Nrup linux-2.6.9-rc2/arch/s390/mm/mmap.c linux-2.6.9-rc2-gap4/arch/s390/mm/mmap.c --- linux-2.6.9-rc2/arch/s390/mm/mmap.c 2004-09-16 11:18:19.855787673 +0200 +++ linux-2.6.9-rc2-gap4/arch/s390/mm/mmap.c 2004-09-17 12:15:23.054452086 +0200 @@ -30,10 +30,13 @@ /* * Top of mmap area (just below the process stack). * - * Leave an at least ~128 MB hole. + * Leave an at least 1 MB hole between stack and mmap_base. + * Leave an at least 128 MB gap between TASK_SIZE and mmap_base with a + * soft rlimit stack. */ -#define MIN_GAP (128*1024*1024) -#define MAX_GAP (TASK_SIZE/6*5) +#define MIN_HOLE (1*1024*1024) +#define MIN_GAP (128*1024*1024 - MIN_HOLE) +#define MAX_GAP (TASK_SIZE/6*5 - MIN_HOLE) static inline unsigned long mmap_base(void) { @@ -43,8 +46,11 @@ static inline unsigned long mmap_base(vo gap = MIN_GAP; else if (gap > MAX_GAP) gap = MAX_GAP; + if ((gap > current->rlim[RLIMIT_STACK].rlim_max) && + !capable(CAP_SYS_RESOURCE)) + gap = current->rlim[RLIMIT_STACK].rlim_max; - return TASK_SIZE - (gap & PAGE_MASK); + return TASK_SIZE - ((gap + MIN_HOLE) & PAGE_MASK); } static inline int mmap_is_legacy(void) - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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