The patch titled
mm: xip/ext2 fix block allocation race
has been added to the -mm tree. Its filename is
mm-xip-ext2-fix-block-allocation-race.patch
Before you just go and hit "reply", please:
a) Consider who else should be cc'ed
b) Prefer to cc a suitable mailing list as well
c) Ideally: find the original patch on the mailing list and do a
reply-to-all to that, adding suitable additional cc's
*** Remember to use Documentation/SubmitChecklist when testing your code ***
See http://www.zip.com.au/~akpm/linux/patches/stuff/added-to-mm.txt to find
out what to do about this
The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/
------------------------------------------------------
Subject: mm: xip/ext2 fix block allocation race
From: Nick Piggin <npiggin@xxxxxxx>
XIP can call into get_xip_mem concurrently with the same file,offset with
create=1. This usually maps down to get_block, which expects the page
lock to prevent such a situation. This causes ext2 to explode for one
reason or another.
Serialise those calls for the moment. For common usages today, I suspect
get_xip_mem rarely is called to create new blocks. In future as XIP
technologies evolve we might need to look at which operations require
scalability, and rework the locking to suit.
Signed-off-by: Nick Piggin <npiggin@xxxxxxx>
Cc: Jared Hulbert <jaredeh@xxxxxxxxx>
Acked-by: Carsten Otte <cotte@xxxxxxxxxx>
Cc: Hugh Dickins <hugh@xxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/filemap_xip.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)
diff -puN mm/filemap_xip.c~mm-xip-ext2-fix-block-allocation-race mm/filemap_xip.c
--- a/mm/filemap_xip.c~mm-xip-ext2-fix-block-allocation-race
+++ a/mm/filemap_xip.c
@@ -248,15 +248,16 @@ again:
int err;
/* maybe shared writable, allocate new block */
+ mutex_lock(&xip_sparse_mutex);
error = mapping->a_ops->get_xip_mem(mapping, vmf->pgoff, 1,
&xip_mem, &xip_pfn);
+ mutex_unlock(&xip_sparse_mutex);
if (error)
return VM_FAULT_SIGBUS;
/* unmap sparse mappings at pgoff from all other vmas */
__xip_unmap(mapping, vmf->pgoff);
found:
- printk("%s insert %lx@%lx\n", current->comm, (unsigned long)vmf->virtual_address, xip_pfn);
err = vm_insert_mixed(vma, (unsigned long)vmf->virtual_address,
xip_pfn);
if (err == -ENOMEM)
@@ -340,8 +341,10 @@ __xip_file_write(struct file *filp, cons
&xip_mem, &xip_pfn);
if (status == -ENODATA) {
/* we allocate a new page unmap it */
+ mutex_lock(&xip_sparse_mutex);
status = a_ops->get_xip_mem(mapping, index, 1,
&xip_mem, &xip_pfn);
+ mutex_unlock(&xip_sparse_mutex);
if (!status)
/* unmap page at pgoff from all other vmas */
__xip_unmap(mapping, index);
_
Patches currently in -mm which might be from npiggin@xxxxxxx are
origin.patch
linux-next.patch
mm-dirty-page-tracking-race-fix.patch
mm-dirty-page-tracking-race-fix-fix.patch
mm-xip-fix-fault-vs-sparse-page-invalidate-race.patch
mm-xip-ext2-fix-block-allocation-race.patch
vmscan-move-isolate_lru_page-to-vmscanc.patch
mlock-mlocked-pages-are-unevictable.patch
mmap-handle-mlocked-pages-during-map-remap-unmap.patch
vmstat-mlocked-pages-statistics.patch
reiser4.patch
likeliness-accounting-change-and-cleanup.patch
--
To unsubscribe from this list: send the line "unsubscribe mm-commits" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
