Commit graph

109 commits

Author SHA1 Message Date
David Howells
ad25f5cb39 rxrpc: Fix locking issue
There's a locking issue with the per-netns list of calls in rxrpc.  The
pieces of code that add and remove a call from the list use write_lock()
and the calls procfile uses read_lock() to access it.  However, the timer
callback function may trigger a removal by trying to queue a call for
processing and finding that it's already queued - at which point it has a
spare refcount that it has to do something with.  Unfortunately, if it puts
the call and this reduces the refcount to 0, the call will be removed from
the list.  Unfortunately, since the _bh variants of the locking functions
aren't used, this can deadlock.

================================
WARNING: inconsistent lock state
5.18.0-rc3-build4+ #10 Not tainted
--------------------------------
inconsistent {SOFTIRQ-ON-W} -> {IN-SOFTIRQ-W} usage.
ksoftirqd/2/25 [HC0[0]:SC1[1]:HE1:SE0] takes:
ffff888107ac4038 (&rxnet->call_lock){+.?.}-{2:2}, at: rxrpc_put_call+0x103/0x14b
{SOFTIRQ-ON-W} state was registered at:
...
 Possible unsafe locking scenario:

       CPU0
       ----
  lock(&rxnet->call_lock);
  <Interrupt>
    lock(&rxnet->call_lock);

 *** DEADLOCK ***

1 lock held by ksoftirqd/2/25:
 #0: ffff8881008ffdb0 ((&call->timer)){+.-.}-{0:0}, at: call_timer_fn+0x5/0x23d

Changes
=======
ver #2)
 - Changed to using list_next_rcu() rather than rcu_dereference() directly.

Fixes: 17926a7932 ("[AF_RXRPC]: Provide secure RxRPC sockets for use by userspace and kernel both")
Signed-off-by: David Howells <dhowells@redhat.com>
cc: Marc Dionne <marc.dionne@auristor.com>
cc: linux-afs@lists.infradead.org
Signed-off-by: David S. Miller <davem@davemloft.net>
2022-05-22 21:03:01 +01:00
Maíra Canal
90b2433edb seq_file: fix NULL pointer arithmetic warning
Implement conditional logic in order to replace NULL pointer arithmetic.

The use of NULL pointer arithmetic was pointed out by clang with the
following warning:

fs/kernfs/file.c:128:15: warning: performing pointer arithmetic on a
null pointer has undefined behavior [-Wnull-pointer-arithmetic]
                return NULL + !*ppos;
                       ~~~~ ^
fs/seq_file.c:559:14: warning: performing pointer arithmetic on a
null pointer has undefined behavior [-Wnull-pointer-arithmetic]
        return NULL + (*pos == 0);

Signed-off-by: Maíra Canal <maira.canal@usp.br>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2022-02-01 11:31:55 -05:00
Andy Shevchenko
372904c080 seq_file: move seq_escape() to a header
Move seq_escape() to the header as inliner, for a small kernel text size
reduction.

Link: https://lkml.kernel.org/r/20211001122917.67228-1-andriy.shevchenko@linux.intel.com
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-11-09 10:02:52 -08:00
Eric Sandeen
8cae8cd89f seq_file: disallow extremely large seq buffer allocations
There is no reasonable need for a buffer larger than this, and it avoids
int overflow pitfalls.

Fixes: 058504edd0 ("fs/seq_file: fallback to vmalloc allocation")
Suggested-by: Al Viro <viro@zeniv.linux.org.uk>
Reported-by: Qualys Security Advisory <qsa@qualys.com>
Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Cc: stable@kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-07-19 17:18:48 -07:00
Andy Shevchenko
cc72181a65 seq_file: drop unused *_escape_mem_ascii()
There are no more users of the seq_escape_mem_ascii() followed by
string_escape_mem_ascii().

Remove them for good.

Link: https://lkml.kernel.org/r/20210504180819.73127-16-andriy.shevchenko@linux.intel.com
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Chuck Lever <chuck.lever@oracle.com>
Cc: "J. Bruce Fields" <bfields@fieldses.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-07-01 11:06:05 -07:00
Andy Shevchenko
fc3de02eae seq_file: convert seq_escape() to use seq_escape_str()
Convert seq_escape() to use seq_escape_str() rather than open coding it.

Note, for now we leave it as an exported symbol due to some old code that
can't tolerate ctype.h being (indirectly) included.

Link: https://lkml.kernel.org/r/20210504180819.73127-14-andriy.shevchenko@linux.intel.com
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Chuck Lever <chuck.lever@oracle.com>
Cc: "J. Bruce Fields" <bfields@fieldses.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-07-01 11:06:05 -07:00
Andy Shevchenko
1d31aa172a seq_file: introduce seq_escape_mem()
Introduce seq_escape_mem() to allow users to pass additional parameters to
string_escape_mem().

Link: https://lkml.kernel.org/r/20210504180819.73127-12-andriy.shevchenko@linux.intel.com
Suggested-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Chuck Lever <chuck.lever@oracle.com>
Cc: "J. Bruce Fields" <bfields@fieldses.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-07-01 11:06:05 -07:00
Florent Revest
76d6a13383 seq_file: Add a seq_bprintf function
Similarly to seq_buf_bprintf in lib/seq_buf.c, this function writes a
printf formatted string with arguments provided in a "binary
representation" built by functions such as vbin_printf.

Signed-off-by: Florent Revest <revest@chromium.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20210427174313.860948-2-revest@chromium.org
2021-04-27 15:50:15 -07:00
Mauro Carvalho Chehab
961f3c898e fs: fix kernel-doc markups
Two markups are at the wrong place. Kernel-doc only
support having the comment just before the identifier.

Also, some identifiers have different names between their
prototypes and the kernel-doc markup.

Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Link: https://lore.kernel.org/r/96b1e1b388600ab092331f6c4e88ff8e8779ce6c.1610610937.git.mchehab+huawei@kernel.org
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2021-01-21 14:06:00 -07:00
Al Viro
4bbf439b09 fix return values of seq_read_iter()
Unlike ->read(), ->read_iter() instances *must* return the amount
of data they'd left in iterator.  For ->read() returning less than
it has actually copied is a QoI issue; read(fd, unmapped_page - 5, 8)
is allowed to fill all 5 bytes of destination and return 4; it's
not nice to caller, but POSIX allows pretty much anything in such
situation, up to and including a SIGSEGV.

generic_file_splice_read() uses pipe-backed iterator as destination;
there a short copy comes from pipe being full, not from running into
an un{mapped,writable} page in the middle of destination as we
have for iovec-backed iterators read(2) uses.  And there we rely
upon the ->read_iter() reporting the actual amount it has left
in destination.

Conversion of a ->read() instance into ->read_iter() has to watch
out for that.  If you really need an "all or nothing" kind of
behaviour somewhere, you need to do iov_iter_revert() to prune
the partial copy.

In case of seq_read_iter() we can handle short copy just fine;
the data is in m->buf and next call will fetch it from there.

Fixes: d4d50710a8 (seq_file: add seq_read_iter)
Tested-by: Nathan Chancellor <natechancellor@gmail.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2020-11-15 22:12:53 -05:00
Christoph Hellwig
d4d50710a8 seq_file: add seq_read_iter
iov_iter based variant for reading a seq_file.  seq_read is
reimplemented on top of the iter variant.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Tested-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-11-06 10:05:18 -08:00
Gustavo A. R. Silva
df561f6688 treewide: Use fallthrough pseudo-keyword
Replace the existing /* fall through */ comments and its variants with
the new pseudo-keyword macro fallthrough[1]. Also, remove unnecessary
fall-through markings when it is the case.

[1] https://www.kernel.org/doc/html/v5.7/process/deprecated.html?highlight=fallthrough#implicit-switch-case-fall-through

Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
2020-08-23 17:36:59 -05:00
Joe Perches
a396301578 fs/seq_file.c: seq_read: Update pr_info_ratelimited
Use a more common logging style.

Add and use pr_fmt, coalesce the format string, align arguments,
use better grammar.

Signed-off-by: Joe Perches <joe@perches.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Vasily Averin <vvs@virtuozzo.com>
Link: http://lkml.kernel.org/r/96ff603230ca1bd60034c36519be3930c3a3a226.camel@perches.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-06-04 19:06:25 -07:00
Vasily Averin
3bfa7e141b fs/seq_file.c: seq_read(): add info message about buggy .next functions
Patch series "seq_file .next functions should increase position index".

In Aug 2018 NeilBrown noticed commit 1f4aace60b ("fs/seq_file.c:
simplify seq_file iteration code and interface")

"Some ->next functions do not increment *pos when they return NULL...
Note that such ->next functions are buggy and should be fixed.  A simple
demonstration is dd if=/proc/swaps bs=1000 skip=1 Choose any block size
larger than the size of /proc/swaps.  This will always show the whole
last line of /proc/swaps"

Described problem is still actual.  If you make lseek into middle of
last output line following read will output end of last line and whole
last line once again.

  $ dd if=/proc/swaps bs=1  # usual output
  Filename				Type		Size	Used	Priority
  /dev/dm-0                             partition	4194812	97536	-2
  104+0 records in
  104+0 records out
  104 bytes copied

  $ dd if=/proc/swaps bs=40 skip=1    # last line was generated twice
  dd: /proc/swaps: cannot skip to specified offset
  v/dm-0                                partition	4194812	97536	-2
  /dev/dm-0                             partition	4194812	97536	-2
  3+1 records in
  3+1 records out
  131 bytes copied

There are lot of other affected files, I've found 30+ including
/proc/net/ip_tables_matches and /proc/sysvipc/*

I've sent patches into maillists of affected subsystems already, this
patch-set fixes the problem in files related to pstore, tracing, gcov,
sysvipc and other subsystems processed via linux-kernel@ mailing list
directly

https://bugzilla.kernel.org/show_bug.cgi?id=206283

This patch (of 4):

Add debug code to seq_read() to detect missed or out-of-tree incorrect
.next seq_file functions.

[akpm@linux-foundation.org: s/pr_info/pr_info_ratelimited/, per Qian Cai]
https://bugzilla.kernel.org/show_bug.cgi?id=206283
Signed-off-by: Vasily Averin <vvs@virtuozzo.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: NeilBrown <neilb@suse.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Manfred Spraul <manfred@colorfullife.com>
Cc: Peter Oberparleiter <oberpar@linux.ibm.com>
Cc: Waiman Long <longman@redhat.com>
Link: http://lkml.kernel.org/r/244674e5-760c-86bd-d08a-047042881748@virtuozzo.com
Link: http://lkml.kernel.org/r/7c24087c-e280-e580-5b0c-0cdaeb14cd18@virtuozzo.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-10 15:36:22 -07:00
Matthew Wilcox (Oracle)
b829a0f0f2 seq_file: remove m->version
The process maps file was the only user of version (introduced back in
2005).  Now that it uses ppos instead, we can remove it.

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Link: http://lkml.kernel.org/r/20200317193201.9924-4-adobriyan@gmail.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-07 10:43:42 -07:00
NeilBrown
6a2aeab59e seq_file: fix problem when seeking mid-record
If you use lseek or similar (e.g.  pread) to access a location in a
seq_file file that is within a record, rather than at a record boundary,
then the first read will return the remainder of the record, and the
second read will return the whole of that same record (instead of the
next record).  When seeking to a record boundary, the next record is
correctly returned.

This bug was introduced by a recent patch (identified below).  Before
that patch, seq_read() would increment m->index when the last of the
buffer was returned (m->count == 0).  After that patch, we rely on
->next to increment m->index after filling the buffer - but there was
one place where that didn't happen.

Link: https://lkml.kernel.org/lkml/877e7xl029.fsf@notabene.neil.brown.name/
Fixes: 1f4aace60b ("fs/seq_file.c: simplify seq_file iteration code and interface")
Signed-off-by: NeilBrown <neilb@suse.com>
Reported-by: Sergei Turchanov <turchanov@farpost.com>
Tested-by: Sergei Turchanov <turchanov@farpost.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Markus Elfring <Markus.Elfring@web.de>
Cc: <stable@vger.kernel.org>	[4.19+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2019-08-13 16:06:52 -07:00
J. Bruce Fields
ea053e164c nfsd: escape high characters in binary data
I'm exposing some information about NFS clients in pseudofiles.  I
expect to eventually have simple tools to help read those pseudofiles.

But it's also helpful if the raw files are human-readable to the extent
possible.  It aids debugging and makes them usable on systems that don't
have the latest nfs-utils.

A minor challenge there is opaque client-generated protocol objects like
state owners and client identifiers.  Some clients generate those to
include handy information in plain ascii.  But they may also include
arbitrary byte sequences.

I think the simplest approach is to limit to isprint(c) && isascii(c)
and escape everything else.

That means you can just cat the file and get something that looks OK.
Also, I'm trying to keep these files legal YAML, which requires them to
UTF-8, and this is a simple way to guarantee that.

Acked-by: Kees Cook <keescook@chromium.org>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
2019-07-03 17:52:50 -04:00
Gustavo A. R. Silva
0a4c92657f fs: mark expected switch fall-throughs
In preparation to enabling -Wimplicit-fallthrough, mark switch cases
where we are expecting to fall through.

This patch fixes the following warnings:

fs/affs/affs.h:124:38: warning: this statement may fall through [-Wimplicit-fallthrough=]
fs/configfs/dir.c:1692:11: warning: this statement may fall through [-Wimplicit-fallthrough=]
fs/configfs/dir.c:1694:7: warning: this statement may fall through [-Wimplicit-fallthrough=]
fs/ceph/file.c:249:3: warning: this statement may fall through [-Wimplicit-fallthrough=]
fs/ext4/hash.c:233:15: warning: this statement may fall through [-Wimplicit-fallthrough=]
fs/ext4/hash.c:246:15: warning: this statement may fall through [-Wimplicit-fallthrough=]
fs/ext2/inode.c:1237:7: warning: this statement may fall through [-Wimplicit-fallthrough=]
fs/ext2/inode.c:1244:7: warning: this statement may fall through [-Wimplicit-fallthrough=]
fs/ext4/indirect.c:1182:6: warning: this statement may fall through [-Wimplicit-fallthrough=]
fs/ext4/indirect.c:1188:6: warning: this statement may fall through [-Wimplicit-fallthrough=]
fs/ext4/indirect.c:1432:6: warning: this statement may fall through [-Wimplicit-fallthrough=]
fs/ext4/indirect.c:1440:6: warning: this statement may fall through [-Wimplicit-fallthrough=]
fs/f2fs/node.c:618:8: warning: this statement may fall through [-Wimplicit-fallthrough=]
fs/f2fs/node.c:620:8: warning: this statement may fall through [-Wimplicit-fallthrough=]
fs/btrfs/ref-verify.c:522:15: warning: this statement may fall through [-Wimplicit-fallthrough=]
fs/gfs2/bmap.c:711:7: warning: this statement may fall through [-Wimplicit-fallthrough=]
fs/gfs2/bmap.c:722:7: warning: this statement may fall through [-Wimplicit-fallthrough=]
fs/jffs2/fs.c:339:6: warning: this statement may fall through [-Wimplicit-fallthrough=]
fs/nfsd/nfs4proc.c:429:12: warning: this statement may fall through [-Wimplicit-fallthrough=]
fs/ufs/util.h:62:6: warning: this statement may fall through [-Wimplicit-fallthrough=]
fs/ufs/util.h:43:6: warning: this statement may fall through [-Wimplicit-fallthrough=]
fs/fcntl.c:770:7: warning: this statement may fall through [-Wimplicit-fallthrough=]
fs/seq_file.c:319:10: warning: this statement may fall through [-Wimplicit-fallthrough=]
fs/libfs.c:148:11: warning: this statement may fall through [-Wimplicit-fallthrough=]
fs/libfs.c:150:7: warning: this statement may fall through [-Wimplicit-fallthrough=]
fs/signalfd.c:178:7: warning: this statement may fall through [-Wimplicit-fallthrough=]
fs/locks.c:1473:16: warning: this statement may fall through [-Wimplicit-fallthrough=]

Warning level 3 was used: -Wimplicit-fallthrough=3

This patch is part of the ongoing efforts to enabling
-Wimplicit-fallthrough.

Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
2019-04-08 18:21:02 -05:00
NeilBrown
1f4aace60b fs/seq_file.c: simplify seq_file iteration code and interface
The documentation for seq_file suggests that it is necessary to be able
to move the iterator to a given offset, however that is not the case.
If the iterator is stored in the private data and is stable from one
read() syscall to the next, it is only necessary to support first/next
interactions.  Implementing this in a client is a little clumsy.

 - if ->start() is given a pos of zero, it should go to start of
   sequence.

 - if ->start() is given the name pos that was given to the most recent
   next() or start(), it should restore the iterator to state just
   before that last call

 - if ->start is given another number, it should set the iterator one
   beyond the start just before the last ->start or ->next call.

Also, the documentation says that the implementation can interpret the
pos however it likes (other than zero meaning start), but seq_file
increments the pos sometimes which does impose on the implementation.

This patch simplifies the interface for first/next iteration and
simplifies the code, while maintaining complete backward compatability.
Now:

 - if ->start() is given a pos of zero, it should return an iterator
   placed at the start of the sequence

 - if ->start() is given a non-zero pos, it should return the iterator
   in the same state it was after the last ->start or ->next.

This is particularly useful for interators which walk the multiple
chains in a hash table, e.g.  using rhashtable_walk*.  See
fs/gfs2/glock.c and drivers/staging/lustre/lustre/llite/vvp_dev.c

A large part of achieving this is to *always* call ->next after ->show
has successfully stored all of an entry in the buffer.  Never just
increment the index instead.  Also:

 - always pass &m->index to ->start() and ->next(), never a temp
   variable

 - don't clear ->from when ->count is zero, as ->from is dead when
   ->count is zero.

Some ->next functions do not increment *pos when they return NULL.  To
maintain compatability with this, we still need to increment m->index in
one place, if ->next didn't increment it.  Note that such ->next
functions are buggy and should be fixed.  A simple demonstration is

   dd if=/proc/swaps bs=1000 skip=1

Choose any block size larger than the size of /proc/swaps.  This will
always show the whole last line of /proc/swaps.

This patch doesn't work around buggy next() functions for this case.

[neilb@suse.com: ensure ->from is valid]
  Link: http://lkml.kernel.org/r/87601ryb8a.fsf@notabene.neil.brown.name
Signed-off-by: NeilBrown <neilb@suse.com>
Acked-by: Jonathan Corbet <corbet@lwn.net>	[docs]
Tested-by: Jann Horn <jannh@google.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Kees Cook <keescook@chromium.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-08-17 16:20:28 -07:00
Hugh Dickins
6c04ab0edd proc: fix smaps and meminfo alignment
The 4.17-rc /proc/meminfo and /proc/<pid>/smaps look ugly: single-digit
numbers (commonly 0) are misaligned.

Remove seq_put_decimal_ull_width()'s leftover optimization for single
digits: it's wrong now that num_to_str() takes care of the width.

Link: http://lkml.kernel.org/r/alpine.LSU.2.11.1805241554210.1326@eggly.anvils
Fixes: d1be35cb6f ("proc: add seq_put_decimal_ull_width to speed up /proc/pid/smaps")
Signed-off-by: Hugh Dickins <hughd@google.com>
Cc: Andrei Vagin <avagin@openvz.org>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-05-25 18:12:11 -07:00
Alexey Dobriyan
d64d01a155 seq_file: account everything to kmemcg
All it takes to open a file and read 1 byte from it.

seq_file will be allocated along with any private allocations, and more
importantly seq file buffer which is 1 page by default.

Link: http://lkml.kernel.org/r/20180310085252.GB17121@avx2
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Glauber Costa <glommer@gmail.com>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-04-11 10:28:36 -07:00
Alexey Dobriyan
0965232035 seq_file: allocate seq_file from kmem_cache
For fine-grained debugging and usercopy protection.

Link: http://lkml.kernel.org/r/20180310085027.GA17121@avx2
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Glauber Costa <glommer@gmail.com>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-04-11 10:28:36 -07:00
Andrei Vagin
48dffbf82d proc: optimize single-symbol delimiters to spead up seq_put_decimal_ull
A delimiter is a string which is printed before a number.  A
syngle-symbol delimiters can be printed by set_putc() and this works
faster than printing by set_puts().

== test_proc.c

int main(int argc, char **argv)
{
	int n, i, fd;
	char buf[16384];

	n = atoi(argv[1]);
	for (i = 0; i < n; i++) {
		fd = open(argv[2], O_RDONLY);
		if (fd < 0)
			return 1;
		if (read(fd, buf, sizeof(buf)) <= 0)
			return 1;
		close(fd);
	}

	return 0;
}
==

$ time ./test_proc  1000000 /proc/1/stat

== Before patch ==
  real	0m3.820s
  user	0m0.337s
  sys	0m3.394s

== After patch ==
  real	0m3.110s
  user	0m0.324s
  sys	0m2.700s

Link: http://lkml.kernel.org/r/20180212074931.7227-3-avagin@openvz.org
Signed-off-by: Andrei Vagin <avagin@openvz.org>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-04-11 10:28:33 -07:00
Andrei Vagin
d1be35cb6f proc: add seq_put_decimal_ull_width to speed up /proc/pid/smaps
seq_put_decimal_ull_w(m, str, val, width) prints a decimal number with a
specified minimal field width.

It is equivalent of seq_printf(m, "%s%*d", str, width, val), but it
works much faster.

== test_smaps.py
  num = 0
  with open("/proc/1/smaps") as f:
          for x in xrange(10000):
                  data = f.read()
                  f.seek(0, 0)
==

== Before patch ==
  $ time python test_smaps.py
  real    0m4.593s
  user    0m0.398s
  sys     0m4.158s

== After patch ==
  $ time python test_smaps.py
  real    0m3.828s
  user    0m0.413s
  sys     0m3.408s

$ perf -g record python test_smaps.py
== Before patch ==
-   79.01%     3.36%  python   [kernel.kallsyms]    [k] show_smap.isra.33
   - 75.65% show_smap.isra.33
      + 48.85% seq_printf
      + 15.75% __walk_page_range
      + 9.70% show_map_vma.isra.23
        0.61% seq_puts

== After patch ==
-   75.51%     4.62%  python   [kernel.kallsyms]    [k] show_smap.isra.33
   - 70.88% show_smap.isra.33
      + 24.82% seq_put_decimal_ull_w
      + 19.78% __walk_page_range
      + 12.74% seq_printf
      + 11.08% show_map_vma.isra.23
      + 1.68% seq_puts

[akpm@linux-foundation.org: fix drivers/of/unittest.c build]
Link: http://lkml.kernel.org/r/20180212074931.7227-1-avagin@openvz.org
Signed-off-by: Andrei Vagin <avagin@openvz.org>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-04-11 10:28:33 -07:00
Andrei Vagin
8cfa67b4d9 procfs: optimize seq_pad() to speed up /proc/pid/maps
seq_printf() is slow and it can be replaced by memset() in this case.

== test.py
  num = 0
  with open("/proc/1/maps") as f:
          while num < 10000 :
                  data = f.read()
                  f.seek(0, 0)
                  num = num + 1
==

== Before patch ==
  $  time python test.py
  real	0m0.986s
  user	0m0.279s
  sys	0m0.707s

== After patch ==
  $ time python test.py
  real	0m0.932s
  user	0m0.261s
  sys	0m0.669s

$ perf record -g python test.py
== Before patch ==
-   47.35%     3.38%  python   [kernel.kallsyms] [k] show_map_vma.isra.23
   - 43.97% show_map_vma.isra.23
      + 20.84% seq_path
      - 15.73% show_vma_header_prefix
      + 6.96% seq_pad
   + 2.94% __GI___libc_read

== After patch ==
-   44.01%     0.34%  python   [kernel.kallsyms] [k] show_pid_map
   - 43.67% show_pid_map
      - 42.91% show_map_vma.isra.23
         + 21.55% seq_path
         - 15.68% show_vma_header_prefix
         + 2.08% seq_pad
        0.55% seq_putc

Link: http://lkml.kernel.org/r/20180112185812.7710-2-avagin@openvz.org
Signed-off-by: Andrei Vagin <avagin@openvz.org>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-04-11 10:28:32 -07:00
Andrei Vagin
0e3dc01914 procfs: add seq_put_hex_ll to speed up /proc/pid/maps
seq_put_hex_ll() prints a number in hexadecimal notation and works
faster than seq_printf().

== test.py
  num = 0
  with open("/proc/1/maps") as f:
          while num < 10000 :
                  data = f.read()
                  f.seek(0, 0)
                 num = num + 1
==

== Before patch ==
  $  time python test.py

  real	0m1.561s
  user	0m0.257s
  sys	0m1.302s

== After patch ==
  $ time python test.py

  real	0m0.986s
  user	0m0.279s
  sys	0m0.707s

$ perf -g record python test.py:

== Before patch ==
-   67.42%     2.82%  python   [kernel.kallsyms] [k] show_map_vma.isra.22
   - 64.60% show_map_vma.isra.22
      - 44.98% seq_printf
         - seq_vprintf
            - vsnprintf
               + 14.85% number
               + 12.22% format_decode
                 5.56% memcpy_erms
      + 15.06% seq_path
      + 4.42% seq_pad
   + 2.45% __GI___libc_read

== After patch ==
-   47.35%     3.38%  python   [kernel.kallsyms] [k] show_map_vma.isra.23
   - 43.97% show_map_vma.isra.23
      + 20.84% seq_path
      - 15.73% show_vma_header_prefix
           10.55% seq_put_hex_ll
         + 2.65% seq_put_decimal_ull
           0.95% seq_putc
      + 6.96% seq_pad
   + 2.94% __GI___libc_read

[avagin@openvz.org: use unsigned int instead of int where it is suitable]
  Link: http://lkml.kernel.org/r/20180214025619.4005-1-avagin@openvz.org
[avagin@openvz.org: v2]
  Link: http://lkml.kernel.org/r/20180117082050.25406-1-avagin@openvz.org
Link: http://lkml.kernel.org/r/20180112185812.7710-1-avagin@openvz.org
Signed-off-by: Andrei Vagin <avagin@openvz.org>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-04-11 10:28:32 -07:00
Miklos Szeredi
cf5eebae2c seq_file: fix incomplete reset on read from zero offset
When resetting iterator on a zero offset we need to discard any data
already in the buffer (count), and private state of the iterator (version).

For example this bug results in first line being repeated in /proc/mounts
if doing a zero size read before a non-zero size read.

Reported-by: Rich Felker <dalias@libc.org>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Fixes: e522751d60 ("seq_file: reset iterator to first record for zero offset")
Cc: <stable@vger.kernel.org> # v4.10
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2018-01-20 02:31:15 -05:00
Greg Kroah-Hartman
b24413180f License cleanup: add SPDX GPL-2.0 license identifier to files with no license
Many source files in the tree are missing licensing information, which
makes it harder for compliance tools to determine the correct license.

By default all files without license information are under the default
license of the kernel, which is GPL version 2.

Update the files which contain no license information with the 'GPL-2.0'
SPDX license identifier.  The SPDX identifier is a legally binding
shorthand, which can be used instead of the full boiler plate text.

This patch is based on work done by Thomas Gleixner and Kate Stewart and
Philippe Ombredanne.

How this work was done:

Patches were generated and checked against linux-4.14-rc6 for a subset of
the use cases:
 - file had no licensing information it it.
 - file was a */uapi/* one with no licensing information in it,
 - file was a */uapi/* one with existing licensing information,

Further patches will be generated in subsequent months to fix up cases
where non-standard license headers were used, and references to license
had to be inferred by heuristics based on keywords.

The analysis to determine which SPDX License Identifier to be applied to
a file was done in a spreadsheet of side by side results from of the
output of two independent scanners (ScanCode & Windriver) producing SPDX
tag:value files created by Philippe Ombredanne.  Philippe prepared the
base worksheet, and did an initial spot review of a few 1000 files.

The 4.13 kernel was the starting point of the analysis with 60,537 files
assessed.  Kate Stewart did a file by file comparison of the scanner
results in the spreadsheet to determine which SPDX license identifier(s)
to be applied to the file. She confirmed any determination that was not
immediately clear with lawyers working with the Linux Foundation.

Criteria used to select files for SPDX license identifier tagging was:
 - Files considered eligible had to be source code files.
 - Make and config files were included as candidates if they contained >5
   lines of source
 - File already had some variant of a license header in it (even if <5
   lines).

All documentation files were explicitly excluded.

The following heuristics were used to determine which SPDX license
identifiers to apply.

 - when both scanners couldn't find any license traces, file was
   considered to have no license information in it, and the top level
   COPYING file license applied.

   For non */uapi/* files that summary was:

   SPDX license identifier                            # files
   ---------------------------------------------------|-------
   GPL-2.0                                              11139

   and resulted in the first patch in this series.

   If that file was a */uapi/* path one, it was "GPL-2.0 WITH
   Linux-syscall-note" otherwise it was "GPL-2.0".  Results of that was:

   SPDX license identifier                            # files
   ---------------------------------------------------|-------
   GPL-2.0 WITH Linux-syscall-note                        930

   and resulted in the second patch in this series.

 - if a file had some form of licensing information in it, and was one
   of the */uapi/* ones, it was denoted with the Linux-syscall-note if
   any GPL family license was found in the file or had no licensing in
   it (per prior point).  Results summary:

   SPDX license identifier                            # files
   ---------------------------------------------------|------
   GPL-2.0 WITH Linux-syscall-note                       270
   GPL-2.0+ WITH Linux-syscall-note                      169
   ((GPL-2.0 WITH Linux-syscall-note) OR BSD-2-Clause)    21
   ((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause)    17
   LGPL-2.1+ WITH Linux-syscall-note                      15
   GPL-1.0+ WITH Linux-syscall-note                       14
   ((GPL-2.0+ WITH Linux-syscall-note) OR BSD-3-Clause)    5
   LGPL-2.0+ WITH Linux-syscall-note                       4
   LGPL-2.1 WITH Linux-syscall-note                        3
   ((GPL-2.0 WITH Linux-syscall-note) OR MIT)              3
   ((GPL-2.0 WITH Linux-syscall-note) AND MIT)             1

   and that resulted in the third patch in this series.

 - when the two scanners agreed on the detected license(s), that became
   the concluded license(s).

 - when there was disagreement between the two scanners (one detected a
   license but the other didn't, or they both detected different
   licenses) a manual inspection of the file occurred.

 - In most cases a manual inspection of the information in the file
   resulted in a clear resolution of the license that should apply (and
   which scanner probably needed to revisit its heuristics).

 - When it was not immediately clear, the license identifier was
   confirmed with lawyers working with the Linux Foundation.

 - If there was any question as to the appropriate license identifier,
   the file was flagged for further research and to be revisited later
   in time.

In total, over 70 hours of logged manual review was done on the
spreadsheet to determine the SPDX license identifiers to apply to the
source files by Kate, Philippe, Thomas and, in some cases, confirmation
by lawyers working with the Linux Foundation.

Kate also obtained a third independent scan of the 4.13 code base from
FOSSology, and compared selected files where the other two scanners
disagreed against that SPDX file, to see if there was new insights.  The
Windriver scanner is based on an older version of FOSSology in part, so
they are related.

Thomas did random spot checks in about 500 files from the spreadsheets
for the uapi headers and agreed with SPDX license identifier in the
files he inspected. For the non-uapi files Thomas did random spot checks
in about 15000 files.

In initial set of patches against 4.14-rc6, 3 files were found to have
copy/paste license identifier errors, and have been fixed to reflect the
correct identifier.

Additionally Philippe spent 10 hours this week doing a detailed manual
inspection and review of the 12,461 patched files from the initial patch
version early this week with:
 - a full scancode scan run, collecting the matched texts, detected
   license ids and scores
 - reviewing anything where there was a license detected (about 500+
   files) to ensure that the applied SPDX license was correct
 - reviewing anything where there was no detection but the patch license
   was not GPL-2.0 WITH Linux-syscall-note to ensure that the applied
   SPDX license was correct

This produced a worksheet with 20 files needing minor correction.  This
worksheet was then exported into 3 different .csv files for the
different types of files to be modified.

These .csv files were then reviewed by Greg.  Thomas wrote a script to
parse the csv files and add the proper SPDX tag to the file, in the
format that the file expected.  This script was further refined by Greg
based on the output to detect more types of files automatically and to
distinguish between header and source .c files (which need different
comment types.)  Finally Greg ran the script using the .csv files to
generate the patches.

Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org>
Reviewed-by: Philippe Ombredanne <pombredanne@nexb.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-11-02 11:10:55 +01:00
Michal Hocko
a7c3e901a4 mm: introduce kv[mz]alloc helpers
Patch series "kvmalloc", v5.

There are many open coded kmalloc with vmalloc fallback instances in the
tree.  Most of them are not careful enough or simply do not care about
the underlying semantic of the kmalloc/page allocator which means that
a) some vmalloc fallbacks are basically unreachable because the kmalloc
part will keep retrying until it succeeds b) the page allocator can
invoke a really disruptive steps like the OOM killer to move forward
which doesn't sound appropriate when we consider that the vmalloc
fallback is available.

As it can be seen implementing kvmalloc requires quite an intimate
knowledge if the page allocator and the memory reclaim internals which
strongly suggests that a helper should be implemented in the memory
subsystem proper.

Most callers, I could find, have been converted to use the helper
instead.  This is patch 6.  There are some more relying on __GFP_REPEAT
in the networking stack which I have converted as well and Eric Dumazet
was not opposed [2] to convert them as well.

[1] http://lkml.kernel.org/r/20170130094940.13546-1-mhocko@kernel.org
[2] http://lkml.kernel.org/r/1485273626.16328.301.camel@edumazet-glaptop3.roam.corp.google.com

This patch (of 9):

Using kmalloc with the vmalloc fallback for larger allocations is a
common pattern in the kernel code.  Yet we do not have any common helper
for that and so users have invented their own helpers.  Some of them are
really creative when doing so.  Let's just add kv[mz]alloc and make sure
it is implemented properly.  This implementation makes sure to not make
a large memory pressure for > PAGE_SZE requests (__GFP_NORETRY) and also
to not warn about allocation failures.  This also rules out the OOM
killer as the vmalloc is a more approapriate fallback than a disruptive
user visible action.

This patch also changes some existing users and removes helpers which
are specific for them.  In some cases this is not possible (e.g.
ext4_kvmalloc, libcfs_kvzalloc) because those seems to be broken and
require GFP_NO{FS,IO} context which is not vmalloc compatible in general
(note that the page table allocation is GFP_KERNEL).  Those need to be
fixed separately.

While we are at it, document that __vmalloc{_node} about unsupported gfp
mask because there seems to be a lot of confusion out there.
kvmalloc_node will warn about GFP_KERNEL incompatible (which are not
superset) flags to catch new abusers.  Existing ones would have to die
slowly.

[sfr@canb.auug.org.au: f2fs fixup]
  Link: http://lkml.kernel.org/r/20170320163735.332e64b7@canb.auug.org.au
Link: http://lkml.kernel.org/r/20170306103032.2540-2-mhocko@kernel.org
Signed-off-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Reviewed-by: Andreas Dilger <adilger@dilger.ca>	[ext4 part]
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: David Miller <davem@davemloft.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-05-08 17:15:12 -07:00
Linus Torvalds
7c0f6ba682 Replace <asm/uaccess.h> with <linux/uaccess.h> globally
This was entirely automated, using the script by Al:

  PATT='^[[:blank:]]*#[[:blank:]]*include[[:blank:]]*<asm/uaccess.h>'
  sed -i -e "s!$PATT!#include <linux/uaccess.h>!" \
        $(git grep -l "$PATT"|grep -v ^include/linux/uaccess.h)

to do the replacement at the end of the merge window.

Requested-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-12-24 11:46:01 -08:00
Tomasz Majchrzak
e522751d60 seq_file: reset iterator to first record for zero offset
If kernfs file is empty on a first read, successive read operations
using the same file descriptor will return no data, even when data is
available. Default kernfs 'seq_next' implementation advances iterator
position even when next object is not there. Kernfs 'seq_start' for
following requests will not return iterator as position is already on
the second object.

This defect doesn't allow to monitor badblocks sysfs files from MD raid.
They are initially empty but if data appears at some stage, userspace is
not able to read it.

Signed-off-by: Tomasz Majchrzak <tomasz.majchrzak@intel.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2016-12-22 23:03:06 -05:00
Joe Perches
75ba1d07fd seq/proc: modify seq_put_decimal_[u]ll to take a const char *, not char
Allow some seq_puts removals by taking a string instead of a single
char.

[akpm@linux-foundation.org: update vmstat_show(), per Joe]
Link: http://lkml.kernel.org/r/667e1cf3d436de91a5698170a1e98d882905e956.1470704995.git.joe@perches.com
Signed-off-by: Joe Perches <joe@perches.com>
Cc: Joe Perches <joe@perches.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-10-07 18:46:30 -07:00
Vegard Nossum
088bf2ff5d fs/seq_file: fix out-of-bounds read
seq_read() is a nasty piece of work, not to mention buggy.

It has (I think) an old bug which allows unprivileged userspace to read
beyond the end of m->buf.

I was getting these:

    BUG: KASAN: slab-out-of-bounds in seq_read+0xcd2/0x1480 at addr ffff880116889880
    Read of size 2713 by task trinity-c2/1329
    CPU: 2 PID: 1329 Comm: trinity-c2 Not tainted 4.8.0-rc1+ #96
    Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.9.3-0-ge2fc41e-prebuilt.qemu-project.org 04/01/2014
    Call Trace:
      kasan_object_err+0x1c/0x80
      kasan_report_error+0x2cb/0x7e0
      kasan_report+0x4e/0x80
      check_memory_region+0x13e/0x1a0
      kasan_check_read+0x11/0x20
      seq_read+0xcd2/0x1480
      proc_reg_read+0x10b/0x260
      do_loop_readv_writev.part.5+0x140/0x2c0
      do_readv_writev+0x589/0x860
      vfs_readv+0x7b/0xd0
      do_readv+0xd8/0x2c0
      SyS_readv+0xb/0x10
      do_syscall_64+0x1b3/0x4b0
      entry_SYSCALL64_slow_path+0x25/0x25
    Object at ffff880116889100, in cache kmalloc-4096 size: 4096
    Allocated:
    PID = 1329
      save_stack_trace+0x26/0x80
      save_stack+0x46/0xd0
      kasan_kmalloc+0xad/0xe0
      __kmalloc+0x1aa/0x4a0
      seq_buf_alloc+0x35/0x40
      seq_read+0x7d8/0x1480
      proc_reg_read+0x10b/0x260
      do_loop_readv_writev.part.5+0x140/0x2c0
      do_readv_writev+0x589/0x860
      vfs_readv+0x7b/0xd0
      do_readv+0xd8/0x2c0
      SyS_readv+0xb/0x10
      do_syscall_64+0x1b3/0x4b0
      return_from_SYSCALL_64+0x0/0x6a
    Freed:
    PID = 0
    (stack is not available)
    Memory state around the buggy address:
     ffff88011688a000: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
     ffff88011688a080: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
    >ffff88011688a100: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
		       ^
     ffff88011688a180: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
     ffff88011688a200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
    ==================================================================
    Disabling lock debugging due to kernel taint

This seems to be the same thing that Dave Jones was seeing here:

  https://lkml.org/lkml/2016/8/12/334

There are multiple issues here:

  1) If we enter the function with a non-empty buffer, there is an attempt
     to flush it. But it was not clearing m->from after doing so, which
     means that if we try to do this flush twice in a row without any call
     to traverse() in between, we are going to be reading from the wrong
     place -- the splat above, fixed by this patch.

  2) If there's a short write to userspace because of page faults, the
     buffer may already contain multiple lines (i.e. pos has advanced by
     more than 1), but we don't save the progress that was made so the
     next call will output what we've already returned previously. Since
     that is a much less serious issue (and I have a headache after
     staring at seq_read() for the past 8 hours), I'll leave that for now.

Link: http://lkml.kernel.org/r/1471447270-32093-1-git-send-email-vegard.nossum@oracle.com
Signed-off-by: Vegard Nossum <vegard.nossum@oracle.com>
Reported-by: Dave Jones <davej@codemonkey.org.uk>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-08-26 17:39:35 -07:00
Linus Torvalds
34dbbcdbf6 Make file credentials available to the seqfile interfaces
A lot of seqfile users seem to be using things like %pK that uses the
credentials of the current process, but that is actually completely
wrong for filesystem interfaces.

The unix semantics for permission checking files is to check permissions
at _open_ time, not at read or write time, and that is not just a small
detail: passing off stdin/stdout/stderr to a suid application and making
the actual IO happen in privileged context is a classic exploit
technique.

So if we want to be able to look at permissions at read time, we need to
use the file open credentials, not the current ones.  Normal file
accesses can just use "f_cred" (or any of the helper functions that do
that, like file_ns_capable()), but the seqfile interfaces do not have
any such options.

It turns out that seq_file _does_ save away the user_ns information of
the file, though.  Since user_ns is just part of the full credential
information, replace that special case with saving off the cred pointer
instead, and suddenly seq_file has all the permission information it
needs.

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-04-14 12:56:09 -07:00
Greg Thelen
0f930902eb fs, seqfile: always allow oom killer
Since 5cec38ac86 ("fs, seq_file: fallback to vmalloc instead of oom kill
processes") seq_buf_alloc() avoids calling the oom killer for PAGE_SIZE or
smaller allocations; but larger allocations can use the oom killer via
vmalloc().  Thus reads of small files can return ENOMEM, but larger files
use the oom killer to avoid ENOMEM.

The effect of this bug is that reads from /proc and other virtual
filesystems can return ENOMEM instead of the preferred behavior - oom
killing something (possibly the calling process).  I don't know of anyone
except Google who has noticed the issue.

I suspect the fix is more needed in smaller systems where there isn't any
reclaimable memory.  But these seem like the kinds of systems which
probably don't use the oom killer for production situations.

Memory overcommit requires use of the oom killer to select a victim
regardless of file size.

Enable oom killer for small seq_buf_alloc() allocations.

Fixes: 5cec38ac86 ("fs, seq_file: fallback to vmalloc instead of oom kill processes")
Signed-off-by: David Rientjes <rientjes@google.com>
Signed-off-by: Greg Thelen <gthelen@google.com>
Acked-by: Eric Dumazet <edumazet@google.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-11-06 17:50:42 -08:00
Andy Shevchenko
25c6bb76ea seq_file: reuse string_escape_str()
strint_escape_str() escapes input string by given criteria.  In case of
seq_escape() the criteria is to convert some characters to their octal
representation.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-11-06 17:50:42 -08:00
Andy Shevchenko
8b91a318e4 fs/seq_file: use seq_* helpers in seq_hex_dump()
This improves code readability.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-11-06 17:50:42 -08:00
Joe Perches
6798a8caaf fs/seq_file: convert int seq_vprint/seq_printf/etc... returns to void
The seq_<foo> function return values were frequently misused.

See: commit 1f33c41c03 ("seq_file: Rename seq_overflow() to
     seq_has_overflowed() and make public")

All uses of these return values have been removed, so convert the
return types to void.

Miscellanea:

o Move seq_put_decimal_<type> and seq_escape prototypes closer the
  other seq_vprintf prototypes
o Reorder seq_putc and seq_puts to return early on overflow
o Add argument names to seq_vprintf and seq_printf
o Update the seq_escape kernel-doc
o Convert a couple of leading spaces to tabs in seq_escape

Signed-off-by: Joe Perches <joe@perches.com>
Cc: Al Viro <viro@ZenIV.linux.org.uk>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Mark Brown <broonie@kernel.org>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Joerg Roedel <jroedel@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-09-11 15:21:34 -07:00
Andy Shevchenko
37607102c4 seq_file: provide an analogue of print_hex_dump()
This introduces a new helper and switches current users to use it.  All
patches are compiled tested. kmemleak is tested via its own test suite.

This patch (of 6):

The new seq_hex_dump() is a complete analogue of print_hex_dump().

We have few users of this functionality already. It allows to reduce their
codebase.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Joe Perches <joe@perches.com>
Cc: Tadeusz Struk <tadeusz.struk@intel.com>
Cc: Helge Deller <deller@gmx.de>
Cc: Ingo Tuchscherer <ingo.tuchscherer@de.ibm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Vladimir Kondratiev <qca_vkondrat@qca.qualcomm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-09-10 13:29:01 -07:00
Linus Torvalds
1dc51b8288 Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs
Pull more vfs updates from Al Viro:
 "Assorted VFS fixes and related cleanups (IMO the most interesting in
  that part are f_path-related things and Eric's descriptor-related
  stuff).  UFS regression fixes (it got broken last cycle).  9P fixes.
  fs-cache series, DAX patches, Jan's file_remove_suid() work"

[ I'd say this is much more than "fixes and related cleanups".  The
  file_table locking rule change by Eric Dumazet is a rather big and
  fundamental update even if the patch isn't huge.   - Linus ]

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (49 commits)
  9p: cope with bogus responses from server in p9_client_{read,write}
  p9_client_write(): avoid double p9_free_req()
  9p: forgetting to cancel request on interrupted zero-copy RPC
  dax: bdev_direct_access() may sleep
  block: Add support for DAX reads/writes to block devices
  dax: Use copy_from_iter_nocache
  dax: Add block size note to documentation
  fs/file.c: __fget() and dup2() atomicity rules
  fs/file.c: don't acquire files->file_lock in fd_install()
  fs:super:get_anon_bdev: fix race condition could cause dev exceed its upper limitation
  vfs: avoid creation of inode number 0 in get_next_ino
  namei: make set_root_rcu() return void
  make simple_positive() public
  ufs: use dir_pages instead of ufs_dir_pages()
  pagemap.h: move dir_pages() over there
  remove the pointless include of lglock.h
  fs: cleanup slight list_entry abuse
  xfs: Correctly lock inode when removing suid and file capabilities
  fs: Call security_ops->inode_killpriv on truncate
  fs: Provide function telling whether file_remove_privs() will do anything
  ...
2015-07-04 19:36:06 -07:00
Linus Torvalds
2d01eedf1d Merge branch 'akpm' (patches from Andrew)
Merge third patchbomb from Andrew Morton:

 - the rest of MM

 - scripts/gdb updates

 - ipc/ updates

 - lib/ updates

 - MAINTAINERS updates

 - various other misc things

* emailed patches from Andrew Morton <akpm@linux-foundation.org>: (67 commits)
  genalloc: rename of_get_named_gen_pool() to of_gen_pool_get()
  genalloc: rename dev_get_gen_pool() to gen_pool_get()
  x86: opt into HAVE_COPY_THREAD_TLS, for both 32-bit and 64-bit
  MAINTAINERS: add zpool
  MAINTAINERS: BCACHE: Kent Overstreet has changed email address
  MAINTAINERS: move Jens Osterkamp to CREDITS
  MAINTAINERS: remove unused nbd.h pattern
  MAINTAINERS: update brcm gpio filename pattern
  MAINTAINERS: update brcm dts pattern
  MAINTAINERS: update sound soc intel patterns
  MAINTAINERS: remove website for paride
  MAINTAINERS: update Emulex ocrdma email addresses
  bcache: use kvfree() in various places
  libcxgbi: use kvfree() in cxgbi_free_big_mem()
  target: use kvfree() in session alloc and free
  IB/ehca: use kvfree() in ipz_queue_{cd}tor()
  drm/nouveau/gem: use kvfree() in u_free()
  drm: use kvfree() in drm_free_large()
  cxgb4: use kvfree() in t4_free_mem()
  cxgb3: use kvfree() in cxgb_free_mem()
  ...
2015-07-01 17:47:51 -07:00
Yann Droneaud
460b865e53 fs: document seq_open()'s usage of file->private_data
seq_open() stores its struct seq_file in file->private_data, thus it must
not be modified by user of seq_file.

Link: http://lkml.kernel.org/r/cover.1433193673.git.ydroneaud@opteya.com
Signed-off-by: Yann Droneaud <ydroneaud@opteya.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-06-30 19:44:57 -07:00
Yann Droneaud
189f9841de fs: allocate structure unconditionally in seq_open()
Since patch described below, from v2.6.15-rc1, seq_open() could use a
struct seq_file already allocated by the caller if the pointer to the
structure is stored in file->private_data before calling the function.

    Commit 1abe77b0fc
    Author: Al Viro <viro@zeniv.linux.org.uk>
    Date:   Mon Nov 7 17:15:34 2005 -0500

        [PATCH] allow callers of seq_open do allocation themselves

        Allow caller of seq_open() to kmalloc() seq_file + whatever else they
        want and set ->private_data to it.  seq_open() will then abstain from
        doing allocation itself.

As there's no more use for such feature, as it could be easily replaced by
calls to seq_open_private() (see commit 39699037a5 ("[FS] seq_file:
Introduce the seq_open_private()")) and seq_release_private() (see
v2.6.0-test3), support for this uncommon feature can be removed from
seq_open().

Link: http://lkml.kernel.org/r/cover.1433193673.git.ydroneaud@opteya.com
Signed-off-by: Yann Droneaud <ydroneaud@opteya.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-06-30 19:44:57 -07:00
Miklos Szeredi
2726d56620 vfs: add seq_file_path() helper
Turn
	seq_path(..., &file->f_path, ...);
into
	seq_file_path(..., file, ...);

Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2015-06-23 18:01:07 -04:00
Omar Sandoval
c8d3fe028f Btrfs: show subvol= and subvolid= in /proc/mounts
Now that we're guaranteed to have a meaningful root dentry, we can just
export seq_dentry() and use it in btrfs_show_options(). The subvolume ID
is easy to get and can also be useful, so put that in there, too.

Reviewed-by: David Sterba <dsterba@suse.cz>
Signed-off-by: Omar Sandoval <osandov@osandov.com>
Signed-off-by: Chris Mason <clm@fb.com>
2015-06-03 04:03:02 -07:00
Tejun Heo
46385326cc bitmap, cpumask, nodemask: remove dedicated formatting functions
Now that all bitmap formatting usages have been converted to
'%*pb[l]', the separate formatting functions are unnecessary.  The
following functions are removed.

* bitmap_scn[list]printf()
* cpumask_scnprintf(), cpulist_scnprintf()
* [__]nodemask_scnprintf(), [__]nodelist_scnprintf()
* seq_bitmap[_list](), seq_cpumask[_list](), seq_nodemask[_list]()
* seq_buf_bitmask()

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-02-13 21:21:39 -08:00
David Rientjes
5cec38ac86 fs, seq_file: fallback to vmalloc instead of oom kill processes
Since commit 058504edd0 ("fs/seq_file: fallback to vmalloc allocation"),
seq_buf_alloc() falls back to vmalloc() when the kmalloc() for contiguous
memory fails.  This was done to address order-4 slab allocations for
reading /proc/stat on large machines and noticed because
PAGE_ALLOC_COSTLY_ORDER < 4, so there is no infinite loop in the page
allocator when allocating new slab for such high-order allocations.

Contiguous memory isn't necessary for caller of seq_buf_alloc(), however.
Other GFP_KERNEL high-order allocations that are <=
PAGE_ALLOC_COSTLY_ORDER will simply loop forever in the page allocator and
oom kill processes as a result.

We don't want to kill processes so that we can allocate contiguous memory
in situations when contiguous memory isn't necessary.

This patch does the kmalloc() allocation with __GFP_NORETRY for high-order
allocations.  This still utilizes memory compaction and direct reclaim in
the allocation path, the only difference is that it will fail immediately
instead of oom kill processes when out of memory.

[akpm@linux-foundation.org: add comment]
Signed-off-by: David Rientjes <rientjes@google.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-12-13 12:42:49 -08:00
Joe Perches
1f33c41c03 seq_file: Rename seq_overflow() to seq_has_overflowed() and make public
The return values of seq_printf/puts/putc are frequently misused.

Start down a path to remove all the return value uses of these
functions.

Move the seq_overflow() to a global inlined function called
seq_has_overflowed() that can be used by the users of seq_file() calls.

Update the documentation to not show return types for seq_printf
et al.  Add a description of seq_has_overflowed().

Link: http://lkml.kernel.org/p/848ac7e3d1c31cddf638a8526fa3c59fa6fdeb8a.1412031505.git.joe@perches.com

Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Joe Perches <joe@perches.com>
[ Reworked the original patch from Joe ]
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2014-10-29 20:26:06 -04:00
Heiko Carstens
058504edd0 fs/seq_file: fallback to vmalloc allocation
There are a couple of seq_files which use the single_open() interface.
This interface requires that the whole output must fit into a single
buffer.

E.g.  for /proc/stat allocation failures have been observed because an
order-4 memory allocation failed due to memory fragmentation.  In such
situations reading /proc/stat is not possible anymore.

Therefore change the seq_file code to fallback to vmalloc allocations
which will usually result in a couple of order-0 allocations and hence
also work if memory is fragmented.

For reference a call trace where reading from /proc/stat failed:

  sadc: page allocation failure: order:4, mode:0x1040d0
  CPU: 1 PID: 192063 Comm: sadc Not tainted 3.10.0-123.el7.s390x #1
  [...]
  Call Trace:
    show_stack+0x6c/0xe8
    warn_alloc_failed+0xd6/0x138
    __alloc_pages_nodemask+0x9da/0xb68
    __get_free_pages+0x2e/0x58
    kmalloc_order_trace+0x44/0xc0
    stat_open+0x5a/0xd8
    proc_reg_open+0x8a/0x140
    do_dentry_open+0x1bc/0x2c8
    finish_open+0x46/0x60
    do_last+0x382/0x10d0
    path_openat+0xc8/0x4f8
    do_filp_open+0x46/0xa8
    do_sys_open+0x114/0x1f0
    sysc_tracego+0x14/0x1a

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Tested-by: David Rientjes <rientjes@google.com>
Cc: Ian Kent <raven@themaw.net>
Cc: Hendrik Brueckner <brueckner@linux.vnet.ibm.com>
Cc: Thorsten Diehl <thorsten.diehl@de.ibm.com>
Cc: Andrea Righi <andrea@betterlinux.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Stefan Bader <stefan.bader@canonical.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-07-03 09:21:54 -07:00
Al Viro
801a76050b seq_file: always clear m->count when we free m->buf
Once we'd freed m->buf, m->count should become zero - we have no valid
contents reachable via m->buf.

Reported-by: Charley (Hao Chuan) Chu <charley.chu@broadcom.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-11-18 19:07:53 -08:00