Alex Bligh [Fri, 16 Dec 2011 04:49:26 +0000 (15:49 +1100)]
net/netfilter/nf_conntrack_netlink.c: fix Oops on container destroy
Problem:
A repeatable Oops can be caused if a container with networking
unshared is destroyed when it has nf_conntrack entries yet to expire.
A copy of the oops follows below. A perl program generating the oops
repeatably is attached inline below.
Analysis:
The oops is called from cleanup_net when the namespace is
destroyed. conntrack iterates through outstanding events and calls
death_by_timeout on each of them, which in turn produces a call to
ctnetlink_conntrack_event. This calls nf_netlink_has_listeners, which
oopses because net->nfnl is NULL.
The perl program generates the container through fork() then
clone(NS_NEWNET). I does not explicitly set up netlink
explicitly set up netlink, but I presume it was set up else net->nfnl
would have been NULL earlier (i.e. when an earlier connection
timed out). This would thus suggest that net->nfnl is made NULL
during the destruction of the container, which I think is done by
nfnetlink_net_exit_batch.
I can see that the various subsystems are deinitialised in the opposite
order to which the relevant register_pernet_subsys calls are called,
and both nf_conntrack and nfnetlink_net_ops register their relevant
subsystems. If nfnetlink_net_ops registered later than nfconntrack,
then its exit routine would have been called first, which would cause
the oops described. I am not sure there is anything to prevent this
happening in a container environment.
Whilst there's perhaps a more complex problem revolving around ordering
of subsystem deinit, it seems to me that missing a netlink event on a
container that is dying is not a disaster. An early check for net->nfnl
being non-NULL in ctnetlink_conntrack_event appears to fix this. There
may remain a potential race condition if it becomes NULL immediately
after being checked (I am not sure any lock is held at this point or
how synchronisation for subsystem deinitialization works).
Patch:
The patch attached should apply on everything from 2.6.26 (if not before)
onwards; it appears to be a problem on all kernels. This was taken against
Ubuntu-3.0.0-11.17 which is very close to 3.0.4. I have torture-tested it
with the above perl script for 15 minutes or so; the perl script hung the
machine within 20 seconds without this patch.
Applicability:
If this is the right solution, it should be applied to all stable kernels
as well as head. Apart from the minor overhead of checking one variable
against NULL, it can never 'do the wrong thing', because if net->nfnl
is NULL, an oops will inevitably result. Therefore, checking is a reasonable
thing to do unless it can be proven than net->nfnl will never be NULL.
Check net->nfnl for NULL in ctnetlink_conntrack_event to avoid Oops on
container destroy
Signed-off-by: Alex Bligh <alex@alex.org.uk> Cc: Patrick McHardy <kaber@trash.net> Cc: David Miller <davem@davemloft.net> Cc: <stable@kernel.org> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
binary_sysctl() calls sysctl_getname() which allocates from names_cache
slab usin __getname()
The matching function to free the name is __putname(), and not putname()
which should be used only to match getname() allocations.
This is because when auditing is enabled, putname() calls audit_putname
*instead* (not in addition) to __putname(). Then, if a syscall is in
progress, audit_putname does not release the name - instead, it expects
the name to get released when the syscall completes, but that will happen
only if audit_getname() was called previously, i.e. if the name was
allocated with getname() rather than the naked __getname(). So,
__getname() followed by putname() ends up leaking memory.
Signed-off-by: Michel Lespinasse <walken@google.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Christoph Hellwig <hch@infradead.org> Cc: Eric Paris <eparis@redhat.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
where the oom score computation was divided into several steps and it's no
longer computed as one expression in unsigned long(rss, swapents, nr_pte
are unsigned long), where the result value assigned to points(int) is in
range(1..1000). So there could be an int overflow while computing
176 points *= 1000;
and points may have negative value. Meaning the oom score for a mem hog task
will be one.
196 if (points <= 0)
197 return 1;
For example:
[ 3366] 0 3366 3539048024303939 5 0 0 oom01
Out of memory: Kill process 3366 (oom01) score 1 or sacrifice child
Here the oom1 process consumes more than 24303939(rss)*4096~=92GB physical
memory, but it's oom score is one.
In this situation the mem hog task is skipped and oom killer kills another and
most probably innocent task with oom score greater than one.
The points variable should be of type long instead of int to prevent the
int overflow.
Haogang Chen [Fri, 16 Dec 2011 04:49:23 +0000 (15:49 +1100)]
nilfs2: potential integer overflow in nilfs_ioctl_clean_segments()
There is a potential integer overflow in nilfs_ioctl_clean_segments().
When a large argv[n].v_nmembs is passed from the userspace, the subsequent
call to vmalloc() will allocate a buffer smaller than expected, which
leads to out-of-bound access in nilfs_ioctl_move_blocks() and
lfs_clean_segments().
The following check does not prevent the overflow because nsegs is also
controlled by the userspace and could be very large.
if (argv[n].v_nmembs > nsegs * nilfs->ns_blocks_per_segment)
goto out_free;
This patch clamps argv[n].v_nmembs to UINT_MAX / argv[n].v_size, and
returns -EINVAL when overflow.
memcg: add mem_cgroup_replace_page_cache() to fix LRU issue
Commit ef6a3c6311 ("mm: add replace_page_cache_page() function") added a
function replace_page_cache_page(). This function replaces a page in the
radix-tree with a new page. WHen doing this, memory cgroup needs to fix
up the accounting information. memcg need to check PCG_USED bit etc.
In some(many?) cases, 'newpage' is on LRU before calling
replace_page_cache(). So, memcg's LRU accounting information should be
fixed, too.
This patch adds mem_cgroup_replace_page_cache() and removes the old hooks.
In that function, old pages will be unaccounted without touching
res_counter and new page will be accounted to the memcg (of old page).
WHen overwriting pc->mem_cgroup of newpage, take zone->lru_lock and avoid
races with LRU handling.
Background:
replace_page_cache_page() is called by FUSE code in its splice() handling.
Here, 'newpage' is replacing oldpage but this newpage is not a newly allocated
page and may be on LRU. LRU mis-accounting will be critical for memory cgroup
because rmdir() checks the whole LRU is empty and there is no account leak.
If a page is on the other LRU than it should be, rmdir() will fail.
Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Michal Hocko <mhocko@suse.cz> Cc: Miklos Szeredi <mszeredi@suse.cz> Cc: Hugh Dickins <hughd@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Here's a cleaner way of doing it, we can extend it to mm/slab.c later.
Please fold into
cpusets-stall-when-updating-mems_allowed-for-mempolicy-or-disjoint-nodemask.patch.
Signed-off-by: David Rientjes <rientjes@google.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Miao Xie <miaox@cn.fujitsu.com> Cc: Paul Menage <paul@paulmenage.org> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
David Rientjes [Fri, 16 Dec 2011 04:49:21 +0000 (15:49 +1100)]
cpusets: stall when updating mems_allowed for mempolicy or disjoint nodemask
Kernels where MAX_NUMNODES > BITS_PER_LONG may temporarily see an empty
nodemask in a tsk's mempolicy if its previous nodemask is remapped onto a
new set of allowed cpuset nodes where the two nodemasks, as a result of
the remap, are now disjoint.
c0ff7453bb5c ("cpuset,mm: fix no node to alloc memory when changing
cpuset's mems") adds get_mems_allowed() to prevent the set of allowed
nodes from changing for a thread. This causes any update to a set of
allowed nodes to stall until put_mems_allowed() is called.
This stall is unncessary, however, if at least one node remains unchanged
in the update to the set of allowed nodes. This was addressed by 89e8a244b97e ("cpusets: avoid looping when storing to mems_allowed if one
node remains set"), but it's still possible that an empty nodemask may be
read from a mempolicy because the old nodemask may be remapped to the new
nodemask during rebind. To prevent this, only avoid the stall if there is
no mempolicy for the thread being changed.
This is a temporary solution until all reads from mempolicy nodemasks can
be guaranteed to not be empty without the get_mems_allowed()
synchronization.
Also moves the check for nodemask intersection inside task_lock() so that
tsk->mems_allowed cannot change. This ensures that nothing can set this
tsk's mems_allowed out from under us and also protects tsk->mempolicy.
Reported-by: Miao Xie <miaox@cn.fujitsu.com> Signed-off-by: David Rientjes <rientjes@google.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Paul Menage <paul@paulmenage.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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