[RFC] [PATCH] madvise() does not always return -EBADF on non-file mapped area

[suzuki <suzuki@in.ibm.com>]

hi,

madvise() system call returns -EBADF for areas which does not map to 
files, only for *behaviour* request MADV_WILLNEED.

Is it the intended behaviour of madvise() ?

According to man pages, madvise returns :

EBADF - the map exists, but the area maps something that isn’t a file.

I have attached a patch which could resolve the issue.

--
regards,

Suzuki K P
Linux Technology Centre,
IBM Software Labs,
India.



Patch to fix madvise() to return -EBADF for non-file mapped area on any 
requested behaviour.

Signed Off by : Suzuki K P <suzuki@in.ibm.com>
================================================

--- mm/madvise.c        2005-07-01 16:08:26.000000000 +0530
+++ mm/madvise.c.new    2005-07-01 16:07:45.000000000 +0530
@@ -62,9 +62,6 @@ static long madvise_willneed(struct vm_a
 {
        struct file *file = vma->vm_file;

-       if (!file)
-               return -EBADF;
-
        start = ((start - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff;
        if (end > vma->vm_end)
                end = vma->vm_end;
@@ -114,8 +111,12 @@ static long madvise_dontneed(struct vm_a
 static long madvise_vma(struct vm_area_struct * vma, unsigned long start,
                        unsigned long end, int behavior)
 {
+       struct file* filp = vma->vm_file;
        long error = -EBADF;

+       if(!filp)
+               goto  out;
+
        switch (behavior) {
        case MADV_NORMAL:
        case MADV_SEQUENTIAL:
@@ -136,6 +137,7 @@ static long madvise_vma(struct vm_area_s
                break;
        }

+out:
        return error;
 }

-
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