Re: [PATCH v5] add MAP_UNLOCKED mmap flag

Américo Wang
2010-01-13T14:34:16Z

On Wed, Jan 13, 2010 at 11:31:19AM +0200, Gleb Natapov wrote:
>If application does mlockall(MCL_FUTURE) it is no longer possible to mmap
>file bigger than main memory or allocate big area of anonymous memory
>in a thread safe manner. Sometimes it is desirable to lock everything
>related to program execution into memory, but still be able to mmap
>big file or allocate huge amount of memory and allow OS to swap them on
>demand. MAP_UNLOCKED allows to do that.
>
>Signed-off-by: Gleb Natapov <gleb@redhat.com>

Thanks for keeping working on it.

This version looks fine for me.

Acked-by: WANG Cong <xiyou.wangcong@gmail.com>

>---
>
>I get reports that people find this useful, so resending.
>
> v1->v2
> - adding new flag to all archs
> - fixing typo
> v2->v3
> - one more typo fix
> v3->v4
> - return error if MAP_LOCKED | MAP_UNLOCKED is specified
> v4->v5
> - rebase to latest head
>
>diff --git a/arch/alpha/include/asm/mman.h b/arch/alpha/include/asm/mman.h
>index 99c56d4..cfc51ac 100644
>--- a/arch/alpha/include/asm/mman.h
>+++ b/arch/alpha/include/asm/mman.h
>@@ -30,6 +30,7 @@
> #define MAP_NONBLOCK 0x40000 /* do not block on IO */
> #define MAP_STACK 0x80000 /* give out an address that is best suited for process/thread stacks */
> #define MAP_HUGETLB 0x100000 /* create a huge page mapping */
>+#define MAP_UNLOCKED 0x200000 /* force page unlocking */
>
> #define MS_ASYNC 1 /* sync memory asynchronously */
> #define MS_SYNC 2 /* synchronous memory sync */
>diff --git a/arch/mips/include/asm/mman.h b/arch/mips/include/asm/mman.h
>index c892bfb..3e4d108 100644
>--- a/arch/mips/include/asm/mman.h
>+++ b/arch/mips/include/asm/mman.h
>@@ -48,6 +48,7 @@
> #define MAP_NONBLOCK 0x20000 /* do not block on IO */
> #define MAP_STACK 0x40000 /* give out an address that is best suited for process/thread stacks */
> #define MAP_HUGETLB 0x80000 /* create a huge page mapping */
>+#define MAP_UNLOCKED 0x100000 /* force page unlocking */
>
> /*
> * Flags for msync
>diff --git a/arch/parisc/include/asm/mman.h b/arch/parisc/include/asm/mman.h
>index 9749c8a..4e8b9bf 100644
>--- a/arch/parisc/include/asm/mman.h
>+++ b/arch/parisc/include/asm/mman.h
>@@ -24,6 +24,7 @@
> #define MAP_NONBLOCK 0x20000 /* do not block on IO */
> #define MAP_STACK 0x40000 /* give out an address that is best suited for process/thread stacks */
> #define MAP_HUGETLB 0x80000 /* create a huge page mapping */
>+#define MAP_UNLOCKED 0x100000 /* force page unlocking */
>
> #define MS_SYNC 1 /* synchronous memory sync */
> #define MS_ASYNC 2 /* sync memory asynchronously */
>diff --git a/arch/powerpc/include/asm/mman.h b/arch/powerpc/include/asm/mman.h
>index d4a7f64..7d33f01 100644
>--- a/arch/powerpc/include/asm/mman.h
>+++ b/arch/powerpc/include/asm/mman.h
>@@ -27,6 +27,7 @@
> #define MAP_NONBLOCK 0x10000 /* do not block on IO */
> #define MAP_STACK 0x20000 /* give out an address that is best suited for process/thread stacks */
> #define MAP_HUGETLB 0x40000 /* create a huge page mapping */
>+#define MAP_UNLOCKED 0x80000 /* force page unlocking */
>
> #ifdef __KERNEL__
> #ifdef CONFIG_PPC64
>diff --git a/arch/sparc/include/asm/mman.h b/arch/sparc/include/asm/mman.h
>index c3029ad..f80d203 100644
>--- a/arch/sparc/include/asm/mman.h
>+++ b/arch/sparc/include/asm/mman.h
>@@ -22,6 +22,7 @@
> #define MAP_NONBLOCK 0x10000 /* do not block on IO */
> #define MAP_STACK 0x20000 /* give out an address that is best suited for process/thread stacks */
> #define MAP_HUGETLB 0x40000 /* create a huge page mapping */
>+#define MAP_UNLOCKED 0x80000 /* force page unlocking */
>
> #ifdef __KERNEL__
> #ifndef __ASSEMBLY__
>diff --git a/arch/xtensa/include/asm/mman.h b/arch/xtensa/include/asm/mman.h
>index fca4db4..c62bcd8 100644
>--- a/arch/xtensa/include/asm/mman.h
>+++ b/arch/xtensa/include/asm/mman.h
>@@ -55,6 +55,7 @@
> #define MAP_NONBLOCK 0x20000 /* do not block on IO */
> #define MAP_STACK 0x40000 /* give out an address that is best suited for process/thread stacks */
> #define MAP_HUGETLB 0x80000 /* create a huge page mapping */
>+#define MAP_UNLOCKED 0x100000 /* force page unlocking */
>
> /*
> * Flags for msync
>diff --git a/include/asm-generic/mman.h b/include/asm-generic/mman.h
>index 32c8bd6..59e0f29 100644
>--- a/include/asm-generic/mman.h
>+++ b/include/asm-generic/mman.h
>@@ -12,6 +12,7 @@
> #define MAP_NONBLOCK 0x10000 /* do not block on IO */
> #define MAP_STACK 0x20000 /* give out an address that is best suited for process/thread stacks */
> #define MAP_HUGETLB 0x40000 /* create a huge page mapping */
>+#define MAP_UNLOCKED 0x80000 /* force page unlocking */
>
> #define MCL_CURRENT 1 /* lock all current mappings */
> #define MCL_FUTURE 2 /* lock all future mappings */
>diff --git a/mm/mmap.c b/mm/mmap.c
>index ee22989..4bda220 100644
>--- a/mm/mmap.c
>+++ b/mm/mmap.c
>@@ -962,6 +962,9 @@ unsigned long do_mmap_pgoff(struct file *file, unsigned long addr,
> if (!can_do_mlock())
> return -EPERM;
>
>+ if (flags & MAP_UNLOCKED)
>+ vm_flags &= ~VM_LOCKED;
>+
> /* mlock MCL_FUTURE? */
> if (vm_flags & VM_LOCKED) {
> unsigned long locked, lock_limit;
>@@ -1050,7 +1053,10 @@ SYSCALL_DEFINE6(mmap_pgoff, unsigned long, addr, unsigned long, len,
> struct file *file = NULL;
> unsigned long retval = -EBADF;
>
>- if (!(flags & MAP_ANONYMOUS)) {
>+ if (unlikely((flags & (MAP_LOCKED | MAP_UNLOCKED)) ==
>+ (MAP_LOCKED | MAP_UNLOCKED))) {
>+ return -EINVAL;
>+ } else if (!(flags & MAP_ANONYMOUS)) {
> if (unlikely(flags & MAP_HUGETLB))
> return -EINVAL;
> file = fget(fd);
>--
> Gleb.
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