Re: [PATCH v5] add MAP_UNLOCKED mmap flag

["Américo Wang" <xiyou.wangcong-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>]

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-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>

Thanks for keeping working on it.

This version looks fine for me.

Acked-by: WANG Cong <xiyou.wangcong-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>

>---
>
>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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