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: 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>
diff --git a/mm/mlock.c b/mm/mlock.c
index bce1b22..008ea70 100644
--- a/mm/mlock.c
+++ b/mm/mlock.c
@@ -248,11 +248,24 @@
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 @@
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 @@
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 @@
/* 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