linux-toradex.git/fs, branch v3.13.9

mm: close PageTail race

2014-04-03T19:02:37+00:00

commit 668f9abbd4334e6c29fa8acd71635c4f9101caa7 upstream.

Commit bf6bddf1924e ("mm: introduce compaction and migration for
ballooned pages") introduces page_count(page) into memory compaction
which dereferences page->first_page if PageTail(page).

This results in a very rare NULL pointer dereference on the
aforementioned page_count(page).  Indeed, anything that does
compound_head(), including page_count() is susceptible to racing with
prep_compound_page() and seeing a NULL or dangling page->first_page
pointer.

This patch uses Andrea's implementation of compound_trans_head() that
deals with such a race and makes it the default compound_head()
implementation.  This includes a read memory barrier that ensures that
if PageTail(head) is true that we return a head page that is neither
NULL nor dangling.  The patch then adds a store memory barrier to
prep_compound_page() to ensure page->first_page is set.

This is the safest way to ensure we see the head page that we are
expecting, PageTail(page) is already in the unlikely() path and the
memory barriers are unfortunately required.

Hugetlbfs is the exception, we don't enforce a store memory barrier
during init since no race is possible.

Signed-off-by: David Rientjes 
Cc: Holger Kiehl 
Cc: Christoph Lameter 
Cc: Rafael Aquini 
Cc: Vlastimil Babka 
Cc: Michal Hocko 
Cc: Mel Gorman 
Cc: Andrea Arcangeli 
Cc: Rik van Riel 
Cc: "Kirill A. Shutemov" 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 
Signed-off-by: Greg Kroah-Hartman

switch mnt_hash to hlist

2014-04-03T19:02:37+00:00

commit 38129a13e6e71f666e0468e99fdd932a687b4d7e upstream.

fixes RCU bug - walking through hlist is safe in face of element moves,
since it's self-terminating.  Cyclic lists are not - if we end up jumping
to another hash chain, we'll loop infinitely without ever hitting the
original list head.

[fix for dumb braino folded]

Spotted by: Max Kellermann 
Signed-off-by: Al Viro 
Signed-off-by: Greg Kroah-Hartman

don't bother with propagate_mnt() unless the target is shared

2014-04-03T19:02:37+00:00

commit 0b1b901b5a98bb36943d10820efc796f7cd45ff3 upstream.

If the dest_mnt is not shared, propagate_mnt() does nothing -
there's no mounts to propagate to and thus no copies to create.
Might as well don't bother calling it in that case.

Signed-off-by: Al Viro 
Signed-off-by: Greg Kroah-Hartman

keep shadowed vfsmounts together

2014-04-03T19:02:37+00:00

commit 1d6a32acd70ab18499829c0a9a5dbe2bace72a13 upstream.

preparation to switching mnt_hash to hlist

Signed-off-by: Al Viro 
Signed-off-by: Greg Kroah-Hartman

resizable namespace.c hashes

2014-04-03T19:02:37+00:00

commit 0818bf27c05b2de56c5b2bd08cfae2a939bd5f52 upstream.

* switch allocation to alloc_large_system_hash()
* make sizes overridable by boot parameters (mhash_entries=, mphash_entries=)
* switch mountpoint_hashtable from list_head to hlist_head

Signed-off-by: Al Viro 
Signed-off-by: Greg Kroah-Hartman

make prepend_name() work correctly when called with negative *buflen

2014-04-03T19:02:36+00:00

commit e825196d48d2b89a6ec3a8eff280098d2a78207e upstream.

In all callchains leading to prepend_name(), the value left in *buflen
is eventually discarded unused if prepend_name() has returned a negative.
So we are free to do what prepend() does, and subtract from *buflen
*before* checking for underflow (which turns into checking the sign
of subtraction result, of course).

Signed-off-by: Al Viro 
Signed-off-by: Greg Kroah-Hartman

rcuwalk: recheck mount_lock after mountpoint crossing attempts

2014-04-03T19:02:34+00:00

commit b37199e626b31e1175fb06764c5d1d687723aac2 upstream.

We can get false negative from __lookup_mnt() if an unrelated vfsmount
gets moved.  In that case legitimize_mnt() is guaranteed to fail,
and we will fall back to non-RCU walk... unless we end up running
into a hard error on a filesystem object we wouldn't have reached
if not for that false negative.  IOW, delaying that check until
the end of pathname resolution is wrong - we should recheck right
after we attempt to cross the mountpoint.  We don't need to recheck
unless we see d_mountpoint() being true - in that case even if
we have just raced with mount/umount, we can simply go on as if
we'd come at the moment when the sucker wasn't a mountpoint; if we
run into a hard error as the result, it was a legitimate outcome.
__lookup_mnt() returning NULL is different in that respect, since
it might've happened due to operation on completely unrelated
mountpoint.

Signed-off-by: Al Viro 
Signed-off-by: Greg Kroah-Hartman

ext4: atomically set inode->i_flags in ext4_set_inode_flags()

2014-04-03T19:02:34+00:00

commit 00a1a053ebe5febcfc2ec498bd894f035ad2aa06 upstream.

Use cmpxchg() to atomically set i_flags instead of clearing out the
S_IMMUTABLE, S_APPEND, etc. flags and then setting them from the
EXT4_IMMUTABLE_FL, EXT4_APPEND_FL flags, since this opens up a race
where an immutable file has the immutable flag cleared for a brief
window of time.

Reported-by: John Sullivan 
Signed-off-by: "Theodore Ts'o" 
Signed-off-by: Linus Torvalds 
Signed-off-by: Greg Kroah-Hartman

fs/proc/proc_devtree.c: remove empty /proc/device-tree when no openfirmware exists.

2014-03-31T17:05:16+00:00

commit c1d867a54d426b45da017fbe8e585f8a3064ce8d upstream.

Distribution kernels might want to build in support for /proc/device-tree
for kernels that might end up running on hardware that doesn't support
openfirmware.  This results in an empty /proc/device-tree existing.
Remove it if the OFW root node doesn't exist.

This situation actually confuses grub2, resulting in install failures.
grub2 sees the /proc/device-tree and picks the wrong install target cf.
http://bzr.savannah.gnu.org/lh/grub/trunk/grub/annotate/4300/util/grub-install.in#L311
grub should be more robust, but still, leaving an empty proc dir seems
pointless.

Addresses https://bugzilla.redhat.com/show_bug.cgi?id=818378.

Signed-off-by: Dave Jones 
Cc: Al Viro 
Cc: Paul Mackerras 
Cc: Josh Boyer 
Cc: Benjamin Herrenschmidt 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 
Signed-off-by: Greg Kroah-Hartman

NFSv4: Use the correct net namespace in nfs4_update_server

2014-03-31T17:05:14+00:00

commit 292f503cade2b1d966239ef56a851e6897d1ba92 upstream.

We need to use the same net namespace that was used to resolve
the hostname and sockaddr arguments.

Fixes: 32e62b7c3ef09 (NFS: Add nfs4_update_server)
Cc: Chuck Lever 
Signed-off-by: Trond Myklebust 
Signed-off-by: Greg Kroah-Hartman