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mlock: make mlock error return Posixly Correct

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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: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: Lee Schermerhorn <lee.schermerhorn@hp.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Lee Schermerhorn 2008-10-18 20:26:56 -07:00 committed by Linus Torvalds
parent c11d69d8c8
commit 9978ad583e
2 changed files with 28 additions and 7 deletions
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2
mm/memory.c
View file

@ -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)

33
mm/mlock.c
View file

@ -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