On Wed, 16 Oct 2013 12:32:40 +0100 "Jan Beulich" <JBeulich@xxxxxxxx> wrote:On 16.10.13 at 22:40, Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> wrote:
Commit c4fe24485729fc2cbff324c111e67a1cc2f9adea ("sparc: fix PCI devicehttp://linux-kernel.2935.n7.nabble.com/mmap-for-proc-vmcore-broken-since-3-12-rc1-td729
proc file mmap(2)"), while fixing one problem, introduced two new ones:
- the function truncates the return value from ->get_unmapped_area() on
64-bit architectures,
- _all_ descendants are now required to set .get_unmapped_area to non-
NULL, which wasn't necessary before (and shouldn't be).
Both - afaict - are a result from a too simplistic copy'n'paste from
proc_reg_mmap() done in that change.
This likely also addresses reports like the one at
326.html.
long orig_addr, unsigned long len, unsigned long pgoff, unsigned long flags)
...
--- 3.12-rc5/fs/proc/inode.c
+++ 3.12-rc5-proc-get-unmapped-area/fs/proc/inode.c
@@ -288,12 +288,12 @@ static int proc_reg_mmap(struct file *fi
static unsigned long proc_reg_get_unmapped_area(struct file *file, unsigned
{long, unsigned long, unsigned long);
struct proc_dir_entry *pde = PDE(file_inode(file));
- int rv = -EIO;
- unsigned long (*get_unmapped_area)(struct file *, unsigned long, unsigned
+ unsigned long rv = -EIO;
+
if (use_pde(pde)) {
- get_unmapped_area = pde->proc_fops->get_unmapped_area;
- if (get_unmapped_area)
- rv = get_unmapped_area(file, orig_addr, len, pgoff, flags);
+ rv = (pde->proc_fops->get_unmapped_area
+ ?: current->mm->get_unmapped_area)(file, orig_addr, len,
+ pgoff, flags);
unuse_pde(pde);
}
return rv;
I think these two patches will address the problems:
http://ozlabs.org/~akpm/mmots/broken-out/procfs-fix-unintended-truncation-of-retur
ned-mapped-address.patch
http://ozlabs.org/~akpm/mmots/broken-out/procfs-call-default-get_unmapped_area-on-
mmu-present-architectures.patch
I'll be sending those Linuswards today. Please check them. (I think
your version would break the nommu build).
Yes indeed - I did search for existing patches, but didn't find them.
I see Linus merged them already, so there's no point anymore
sending Reviewed-by tags.
I think though that in the !MMU case the second of them leaves an
issue unfixed nevertheless: If the specific procfs handler has no
.get_unmapped_area, the operation would still fail in that case
rather than succeed as it did before that wrapper got added.)
Jan