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Commit 9978ad58 authored by Lee Schermerhorn's avatar Lee Schermerhorn Committed by Linus Torvalds
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mlock: make mlock error return Posixly Correct 

Rework Posix error return for mlock().

Posix requires error code for mlock*() system calls for some conditions
that differ from what kernel low level functions, such as
get_user_pages(), return for those conditions.  For more info, see:

http://marc.info/?l=linux-kernel&m=121750892930775&w=2



This patch provides the same translation of get_user_pages()
error codes to posix specified error codes in the context
of the mlock rework for unevictable lru.

[akpm@linux-foundation.org: fix build]
Signed-off-by: default avatarKOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: default avatarLee Schermerhorn <lee.schermerhorn@hp.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent c11d69d8

mm/memory.c

+1 −1
Original line number Diff line number Diff line
@@ -2821,7 +2821,7 @@ int make_pages_present(unsigned long addr, unsigned long end) 
			len, write, 0, NULL, NULL);

	if (ret < 0)

		return ret;

	return ret == len ? 0 : -1;

	return ret == len ? 0 : -EFAULT;

}



#if !defined(__HAVE_ARCH_GATE_AREA)

mm/mlock.c

+27 −6
Original line number Diff line number Diff line
@@ -248,11 +248,24 @@ static long __mlock_vma_pages_range(struct vm_area_struct *vma, 
			addr += PAGE_SIZE;	/* for next get_user_pages() */

			nr_pages--;

		}

		ret = 0;

	}



	lru_add_drain_all();	/* to update stats */



	return 0;	/* count entire vma as locked_vm */

	return ret;	/* count entire vma as locked_vm */

}



/*

 * convert get_user_pages() return value to posix mlock() error

 */

static int __mlock_posix_error_return(long retval)

{

	if (retval == -EFAULT)

		retval = -ENOMEM;

	else if (retval == -ENOMEM)

		retval = -EAGAIN;

	return retval;

}



#else /* CONFIG_UNEVICTABLE_LRU */
@@ -265,9 +278,15 @@ static long __mlock_vma_pages_range(struct vm_area_struct *vma, 
				   int mlock)

{

	if (mlock && (vma->vm_flags & VM_LOCKED))

		make_pages_present(start, end);

		return make_pages_present(start, end);

	return 0;

}



static inline int __mlock_posix_error_return(long retval)

{

	return 0;

}



#endif /* CONFIG_UNEVICTABLE_LRU */



/**
@@ -434,10 +453,7 @@ success: 
		downgrade_write(&mm->mmap_sem);



		ret = __mlock_vma_pages_range(vma, start, end, 1);

		if (ret > 0) {

			mm->locked_vm -= ret;

			ret = 0;

		}



		/*

		 * Need to reacquire mmap sem in write mode, as our callers

		 * expect this.  We have no support for atomically upgrading
@@ -451,6 +467,11 @@ success: 
		/* non-NULL *prev must contain @start, but need to check @end */

		if (!(*prev) || end > (*prev)->vm_end)

			ret = -ENOMEM;

		else if (ret > 0) {

			mm->locked_vm -= ret;

			ret = 0;

		} else

			ret = __mlock_posix_error_return(ret); /* translate if needed */

	} else {

		/*

		 * TODO:  for unlocking, pages will already be resident, so