commit 3253d9d093376d62b4a56e609f15d2ec5085ac73 upstream.
Andreas Grünbacher reports that on the two filesystems that support
iomap directio, it's possible for splice() to return -EAGAIN (instead of
a short splice) if the pipe being written to has less space available in
its pipe buffers than the length supplied by the calling process.
Months ago we fixed splice_direct_to_actor to clamp the length of the
read request to the size of the splice pipe. Do the same to do_splice.
Fixes: 17614445576b6 ("splice: don't read more than available pipe space")
Reported-by: syzbot+3c01db6025f26530cf8d@syzkaller.appspotmail.com
Reported-by: Andreas Grünbacher <andreas.gruenbacher@gmail.com>
Reviewed-by: Andreas Grünbacher <andreas.gruenbacher@gmail.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
[ Upstream commit 17614445576b6af24e9cf36607c6448164719c96 ]
In commit 4721a601099, we tried to fix a problem wherein directio reads
into a splice pipe will bounce EFAULT/EAGAIN all the way out to
userspace by simulating a zero-byte short read. This happens because
some directio read implementations (xfs) will call
bio_iov_iter_get_pages to grab pipe buffer pages and issue asynchronous
reads, but as soon as we run out of pipe buffers that _get_pages call
returns EFAULT, which the splice code translates to EAGAIN and bounces
out to userspace.
In that commit, the iomap code catches the EFAULT and simulates a
zero-byte read, but that causes assertion errors on regular splice reads
because xfs doesn't allow short directio reads.
The brokenness is compounded by splice_direct_to_actor immediately
bailing on do_splice_to returning <= 0 without ever calling ->actor
(which empties out the pipe), so if userspace calls back we'll EFAULT
again on the full pipe, and nothing ever gets copied.
Therefore, teach splice_direct_to_actor to clamp its requests to the
amount of free space in the pipe and remove the simulated short read
from the iomap directio code.
Fixes: 4721a601099 ("iomap: dio data corruption and spurious errors when pipes fill")
Reported-by: Murphy Zhou <jencce.kernel@gmail.com>
Ranted-by: Amir Goldstein <amir73il@gmail.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
commit 15fab63e1e57be9fdb5eec1bbc5916e9825e9acb upstream.
Change pipe_buf_get() to return a bool indicating whether it succeeded
in raising the refcount of the page (if the thing in the pipe is a page).
This removes another mechanism for overflowing the page refcount. All
callers converted to handle a failure.
Reported-by: Jann Horn <jannh@google.com>
Signed-off-by: Matthew Wilcox <willy@infradead.org>
Cc: stable@kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit b987222654f84f7b4ca95b3a55eca784cb30235b upstream.
This fixes multiple issues in buffer_pipe_buf_ops:
- The ->steal() handler must not return zero unless the pipe buffer has
the only reference to the page. But generic_pipe_buf_steal() assumes
that every reference to the pipe is tracked by the page's refcount,
which isn't true for these buffers - buffer_pipe_buf_get(), which
duplicates a buffer, doesn't touch the page's refcount.
Fix it by using generic_pipe_buf_nosteal(), which refuses every
attempted theft. It should be easy to actually support ->steal, but the
only current users of pipe_buf_steal() are the virtio console and FUSE,
and they also only use it as an optimization. So it's probably not worth
the effort.
- The ->get() and ->release() handlers can be invoked concurrently on pipe
buffers backed by the same struct buffer_ref. Make them safe against
concurrency by using refcount_t.
- The pointers stored in ->private were only zeroed out when the last
reference to the buffer_ref was dropped. As far as I know, this
shouldn't be necessary anyway, but if we do it, let's always do it.
Link: http://lkml.kernel.org/r/20190404215925.253531-1-jannh@google.com
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: stable@vger.kernel.org
Fixes: 73a757e631 ("ring-buffer: Return reader page back into existing ring buffer")
Signed-off-by: Jann Horn <jannh@google.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit a0ce2f0aa6ad97c3d4927bf2ca54bcebdf062d55 upstream.
Before this patch, it was possible for two pipes to affect each other after
data had been transferred between them with tee():
============
$ cat tee_test.c
int main(void) {
int pipe_a[2];
if (pipe(pipe_a)) err(1, "pipe");
int pipe_b[2];
if (pipe(pipe_b)) err(1, "pipe");
if (write(pipe_a[1], "abcd", 4) != 4) err(1, "write");
if (tee(pipe_a[0], pipe_b[1], 2, 0) != 2) err(1, "tee");
if (write(pipe_b[1], "xx", 2) != 2) err(1, "write");
char buf[5];
if (read(pipe_a[0], buf, 4) != 4) err(1, "read");
buf[4] = 0;
printf("got back: '%s'\n", buf);
}
$ gcc -o tee_test tee_test.c
$ ./tee_test
got back: 'abxx'
$
============
As suggested by Al Viro, fix it by creating a separate type for
non-mergeable pipe buffers, then changing the types of buffers in
splice_pipe_to_pipe() and link_pipe().
Cc: <stable@vger.kernel.org>
Fixes: 7c77f0b3f9 ("splice: implement pipe to pipe splicing")
Fixes: 70524490ee ("[PATCH] splice: add support for sys_tee()")
Suggested-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Jann Horn <jannh@google.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Pull compat updates from Al Viro:
"Some biarch patches - getting rid of assorted (mis)uses of
compat_alloc_user_space().
Not much in that area this cycle..."
* 'work.compat' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
orangefs: simplify compat ioctl handling
signalfd: lift sigmask copyin and size checks to callers of do_signalfd4()
vmsplice(): lift importing iovec into vmsplice(2) and compat counterpart
Using the fs-internal do_vmsplice() helper allows us to get rid of the
fs-internal call to the sys_vmsplice() syscall.
This patch is part of a series which removes in-kernel calls to syscalls.
On this basis, the syscall entry path can be streamlined. For details, see
http://lkml.kernel.org/r/20180325162527.GA17492@light.dominikbrodowski.net
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net>
Please do not apply this to mainline directly, instead please re-run the
coccinelle script shown below and apply its output.
For several reasons, it is desirable to use {READ,WRITE}_ONCE() in
preference to ACCESS_ONCE(), and new code is expected to use one of the
former. So far, there's been no reason to change most existing uses of
ACCESS_ONCE(), as these aren't harmful, and changing them results in
churn.
However, for some features, the read/write distinction is critical to
correct operation. To distinguish these cases, separate read/write
accessors must be used. This patch migrates (most) remaining
ACCESS_ONCE() instances to {READ,WRITE}_ONCE(), using the following
coccinelle script:
----
// Convert trivial ACCESS_ONCE() uses to equivalent READ_ONCE() and
// WRITE_ONCE()
// $ make coccicheck COCCI=/home/mark/once.cocci SPFLAGS="--include-headers" MODE=patch
virtual patch
@ depends on patch @
expression E1, E2;
@@
- ACCESS_ONCE(E1) = E2
+ WRITE_ONCE(E1, E2)
@ depends on patch @
expression E;
@@
- ACCESS_ONCE(E)
+ READ_ONCE(E)
----
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: davem@davemloft.net
Cc: linux-arch@vger.kernel.org
Cc: mpe@ellerman.id.au
Cc: shuah@kernel.org
Cc: snitzer@redhat.com
Cc: thor.thayer@linux.intel.com
Cc: tj@kernel.org
Cc: viro@zeniv.linux.org.uk
Cc: will.deacon@arm.com
Link: http://lkml.kernel.org/r/1508792849-3115-19-git-send-email-paulmck@linux.vnet.ibm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
De-dupliate some code and allow for passing the flags argument to
vfs_iter_write. Additionally it now properly updates timestamps.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Pull splice updates from Al Viro:
"These actually missed the last cycle; the branch itself is from last
December"
* 'work.splice' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
make nr_pages calculation in default_file_splice_read() a bit less ugly
splice/tee/vmsplice: validate flags
splice_pipe_desc: kill ->flags
remove spd_release_page()
Pull sched.h split-up from Ingo Molnar:
"The point of these changes is to significantly reduce the
<linux/sched.h> header footprint, to speed up the kernel build and to
have a cleaner header structure.
After these changes the new <linux/sched.h>'s typical preprocessed
size goes down from a previous ~0.68 MB (~22K lines) to ~0.45 MB (~15K
lines), which is around 40% faster to build on typical configs.
Not much changed from the last version (-v2) posted three weeks ago: I
eliminated quirks, backmerged fixes plus I rebased it to an upstream
SHA1 from yesterday that includes most changes queued up in -next plus
all sched.h changes that were pending from Andrew.
I've re-tested the series both on x86 and on cross-arch defconfigs,
and did a bisectability test at a number of random points.
I tried to test as many build configurations as possible, but some
build breakage is probably still left - but it should be mostly
limited to architectures that have no cross-compiler binaries
available on kernel.org, and non-default configurations"
* 'WIP.sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (146 commits)
sched/headers: Clean up <linux/sched.h>
sched/headers: Remove #ifdefs from <linux/sched.h>
sched/headers: Remove the <linux/topology.h> include from <linux/sched.h>
sched/headers, hrtimer: Remove the <linux/wait.h> include from <linux/hrtimer.h>
sched/headers, x86/apic: Remove the <linux/pm.h> header inclusion from <asm/apic.h>
sched/headers, timers: Remove the <linux/sysctl.h> include from <linux/timer.h>
sched/headers: Remove <linux/magic.h> from <linux/sched/task_stack.h>
sched/headers: Remove <linux/sched.h> from <linux/sched/init.h>
sched/core: Remove unused prefetch_stack()
sched/headers: Remove <linux/rculist.h> from <linux/sched.h>
sched/headers: Remove the 'init_pid_ns' prototype from <linux/sched.h>
sched/headers: Remove <linux/signal.h> from <linux/sched.h>
sched/headers: Remove <linux/rwsem.h> from <linux/sched.h>
sched/headers: Remove the runqueue_is_locked() prototype
sched/headers: Remove <linux/sched.h> from <linux/sched/hotplug.h>
sched/headers: Remove <linux/sched.h> from <linux/sched/debug.h>
sched/headers: Remove <linux/sched.h> from <linux/sched/nohz.h>
sched/headers: Remove <linux/sched.h> from <linux/sched/stat.h>
sched/headers: Remove the <linux/gfp.h> include from <linux/sched.h>
sched/headers: Remove <linux/rtmutex.h> from <linux/sched.h>
...
Fix up affected files that include this signal functionality via sched.h.
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Flags (PIPE_BUF_FLAG_PACKET, PIPE_BUF_FLAG_GIFT) could remain on the
unused part of the pipe ring buffer. Previously splice_to_pipe() left
the flags value alone, which could result in incorrect behavior.
Uninitialized flags appears to have been there from the introduction of
the splice syscall.
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Cc: <stable@vger.kernel.org> # 2.6.17+
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
It's an artifact of lousy calling conventions of iov_iter_get_pages_alloc().
Hopefully, we'll get something saner come next cycle; for now that'll
do.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Commit 8924feff66 ("splice: lift pipe_lock out of splice_to_pipe()")
caused a regression when there were no more readers left on a pipe that
was being spliced into: rather than the expected SIGPIPE and -EPIPE
return value, the writer would end up waiting forever for space to free
up (which obviously was not going to happen with no readers around).
Fixes: 8924feff66 ("splice: lift pipe_lock out of splice_to_pipe()")
Reported-and-tested-by: Andreas Schwab <schwab@linux-m68k.org>
Debugged-by: Al Viro <viro@zeniv.linux.org.uk>
Cc: stable@kernel.org # v4.9
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Pull block layer updates from Jens Axboe:
"This is the main block pull request this series. Contrary to previous
release, I've kept the core and driver changes in the same branch. We
always ended up having dependencies between the two for obvious
reasons, so makes more sense to keep them together. That said, I'll
probably try and keep more topical branches going forward, especially
for cycles that end up being as busy as this one.
The major parts of this pull request is:
- Improved support for O_DIRECT on block devices, with a small
private implementation instead of using the pig that is
fs/direct-io.c. From Christoph.
- Request completion tracking in a scalable fashion. This is utilized
by two components in this pull, the new hybrid polling and the
writeback queue throttling code.
- Improved support for polling with O_DIRECT, adding a hybrid mode
that combines pure polling with an initial sleep. From me.
- Support for automatic throttling of writeback queues on the block
side. This uses feedback from the device completion latencies to
scale the queue on the block side up or down. From me.
- Support from SMR drives in the block layer and for SD. From Hannes
and Shaun.
- Multi-connection support for nbd. From Josef.
- Cleanup of request and bio flags, so we have a clear split between
which are bio (or rq) private, and which ones are shared. From
Christoph.
- A set of patches from Bart, that improve how we handle queue
stopping and starting in blk-mq.
- Support for WRITE_ZEROES from Chaitanya.
- Lightnvm updates from Javier/Matias.
- Supoort for FC for the nvme-over-fabrics code. From James Smart.
- A bunch of fixes from a whole slew of people, too many to name
here"
* 'for-4.10/block' of git://git.kernel.dk/linux-block: (182 commits)
blk-stat: fix a few cases of missing batch flushing
blk-flush: run the queue when inserting blk-mq flush
elevator: make the rqhash helpers exported
blk-mq: abstract out blk_mq_dispatch_rq_list() helper
blk-mq: add blk_mq_start_stopped_hw_queue()
block: improve handling of the magic discard payload
blk-wbt: don't throttle discard or write zeroes
nbd: use dev_err_ratelimited in io path
nbd: reset the setup task for NBD_CLEAR_SOCK
nvme-fabrics: Add FC LLDD loopback driver to test FC-NVME
nvme-fabrics: Add target support for FC transport
nvme-fabrics: Add host support for FC transport
nvme-fabrics: Add FC transport LLDD api definitions
nvme-fabrics: Add FC transport FC-NVME definitions
nvme-fabrics: Add FC transport error codes to nvme.h
Add type 0x28 NVME type code to scsi fc headers
nvme-fabrics: patch target code in prep for FC transport support
nvme-fabrics: set sqe.command_id in core not transports
parser: add u64 number parser
nvme-rdma: align to generic ib_event logging helper
...
Botched calculation of number of pages. As the result,
we were dropping pieces when doing splice to pipe from
e.g. 9p.
Reported-by: Alexei Starovoitov <ast@kernel.org>
Tested-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
i_size check is a leftover from the horrors that used to play with
the page cache in that function. With the switch to ->read_iter(),
it's neither needed nor correct - for gfs2 it ends up being buggy,
since i_size is not guaranteed to be correct until later (inside
->read_iter()).
Spotted-by: Abhi Das <adas@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
It's only needed for the CONFIG_SWAP-only use of bio_end_io_t.
Because CONFIG_SWAP implies CONFIG_BLOCK this will allow to drop some
ifdefs in blk_types.h.
Instead we'll need to add a few explicit includes that were implicit
before, though.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@fb.com>
by making sure we call iov_iter_advance() on original
iov_iter even if direct_IO (done on its copy) has returned 0.
It's a no-op for old iov_iter flavours and does the right thing
(== truncation of the stuff we'd allocated, but not filled) in
ITER_PIPE case. Failures (e.g. -EIO) get caught and dealt with
by cleanup in generic_file_read_iter().
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
we only use iov_iter_get_pages_alloc() and iov_iter_advance() -
pages are filled by kernel_readv() via a kvec array (as we used
to do all along), so iov_iter here is used only as a way of
arranging for those pages to be in pipe.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
iov_iter variant for passing data into pipe. copy_to_iter()
copies data into page(s) it has allocated and stuffs them into
the pipe; copy_page_to_iter() stuffs there a reference to the
page given to it. Both will try to coalesce if possible.
iov_iter_zero() is similar to copy_to_iter(); iov_iter_get_pages()
and friends will do as copy_to_iter() would have and return the
pages where the data would've been copied. iov_iter_advance()
will truncate everything past the spot it has advanced to.
New primitive: iov_iter_pipe(), used for initializing those.
pipe should be locked all along.
Running out of space acts as fault would for iovec-backed ones;
in other words, giving it to ->read_iter() may result in short
read if the pipe overflows, or -EFAULT if it happens with nothing
copied there.
In other words, ->read_iter() on those acts pretty much like
->splice_read(). Moreover, all generic_file_splice_read() users,
as well as many other ->splice_read() instances can be switched
to that scheme - that'll happen in the next commit.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
single-buffer analogue of splice_to_pipe(); vmsplice_to_pipe() switched
to that, leaving splice_to_pipe() only for ->splice_read() instances
(and that only until they are converted as well).
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* splice_to_pipe() stops at pipe overflow and does *not* take pipe_lock
* ->splice_read() instances do the same
* vmsplice_to_pipe() and do_splice() (ultimate callers of splice_to_pipe())
arrange for waiting, looping, etc. themselves.
That should make pipe_lock the outermost one.
Unfortunately, existing rules for the amount passed by vmsplice_to_pipe()
and do_splice() are quite ugly _and_ userland code can be easily broken
by changing those. It's not even "no more than the maximal capacity of
this pipe" - it's "once we'd fed pipe->nr_buffers pages into the pipe,
leave instead of waiting".
Considering how poorly these rules are documented, let's try "wait for some
space to appear, unless given SPLICE_F_NONBLOCK, then push into pipe
and if we run into overflow, we are done".
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
PAGE_CACHE_{SIZE,SHIFT,MASK,ALIGN} macros were introduced *long* time
ago with promise that one day it will be possible to implement page
cache with bigger chunks than PAGE_SIZE.
This promise never materialized. And unlikely will.
We have many places where PAGE_CACHE_SIZE assumed to be equal to
PAGE_SIZE. And it's constant source of confusion on whether
PAGE_CACHE_* or PAGE_* constant should be used in a particular case,
especially on the border between fs and mm.
Global switching to PAGE_CACHE_SIZE != PAGE_SIZE would cause to much
breakage to be doable.
Let's stop pretending that pages in page cache are special. They are
not.
The changes are pretty straight-forward:
- <foo> << (PAGE_CACHE_SHIFT - PAGE_SHIFT) -> <foo>;
- <foo> >> (PAGE_CACHE_SHIFT - PAGE_SHIFT) -> <foo>;
- PAGE_CACHE_{SIZE,SHIFT,MASK,ALIGN} -> PAGE_{SIZE,SHIFT,MASK,ALIGN};
- page_cache_get() -> get_page();
- page_cache_release() -> put_page();
This patch contains automated changes generated with coccinelle using
script below. For some reason, coccinelle doesn't patch header files.
I've called spatch for them manually.
The only adjustment after coccinelle is revert of changes to
PAGE_CAHCE_ALIGN definition: we are going to drop it later.
There are few places in the code where coccinelle didn't reach. I'll
fix them manually in a separate patch. Comments and documentation also
will be addressed with the separate patch.
virtual patch
@@
expression E;
@@
- E << (PAGE_CACHE_SHIFT - PAGE_SHIFT)
+ E
@@
expression E;
@@
- E >> (PAGE_CACHE_SHIFT - PAGE_SHIFT)
+ E
@@
@@
- PAGE_CACHE_SHIFT
+ PAGE_SHIFT
@@
@@
- PAGE_CACHE_SIZE
+ PAGE_SIZE
@@
@@
- PAGE_CACHE_MASK
+ PAGE_MASK
@@
expression E;
@@
- PAGE_CACHE_ALIGN(E)
+ PAGE_ALIGN(E)
@@
expression E;
@@
- page_cache_get(E)
+ get_page(E)
@@
expression E;
@@
- page_cache_release(E)
+ put_page(E)
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Running the following command:
busybox cat /sys/kernel/debug/tracing/trace_pipe > /dev/null
with any tracing enabled pretty very quickly leads to various NULL
pointer dereferences and VM BUG_ON()s, such as these:
BUG: unable to handle kernel NULL pointer dereference at 0000000000000020
IP: [<ffffffff8119df6c>] generic_pipe_buf_release+0xc/0x40
Call Trace:
[<ffffffff811c48a3>] splice_direct_to_actor+0x143/0x1e0
[<ffffffff811c42e0>] ? generic_pipe_buf_nosteal+0x10/0x10
[<ffffffff811c49cf>] do_splice_direct+0x8f/0xb0
[<ffffffff81196869>] do_sendfile+0x199/0x380
[<ffffffff81197600>] SyS_sendfile64+0x90/0xa0
[<ffffffff8192cbee>] entry_SYSCALL_64_fastpath+0x12/0x6d
page dumped because: VM_BUG_ON_PAGE(atomic_read(&page->_count) == 0)
kernel BUG at include/linux/mm.h:367!
invalid opcode: 0000 [#1] PREEMPT SMP DEBUG_PAGEALLOC
RIP: [<ffffffff8119df9c>] generic_pipe_buf_release+0x3c/0x40
Call Trace:
[<ffffffff811c48a3>] splice_direct_to_actor+0x143/0x1e0
[<ffffffff811c42e0>] ? generic_pipe_buf_nosteal+0x10/0x10
[<ffffffff811c49cf>] do_splice_direct+0x8f/0xb0
[<ffffffff81196869>] do_sendfile+0x199/0x380
[<ffffffff81197600>] SyS_sendfile64+0x90/0xa0
[<ffffffff8192cd1e>] tracesys_phase2+0x84/0x89
(busybox's cat uses sendfile(2), unlike the coreutils version)
This is because tracing_splice_read_pipe() can call splice_to_pipe()
with spd->nr_pages == 0. spd_pages underflows in splice_to_pipe() and
we fill the page pointers and the other fields of the pipe_buffers with
garbage.
All other callers of splice_to_pipe() avoid calling it when nr_pages ==
0, and we could make tracing_splice_read_pipe() do that too, but it
seems reasonable to have splice_to_page() handle this condition
gracefully.
Cc: stable@vger.kernel.org
Signed-off-by: Rabin Vincent <rabin@rab.in>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This way we can set kiocb flags also from the sync read/write path for
the read_iter/write_iter operations. For now there is no way to pass
flags to plain read/write operations as there is no real need for that,
and all flags passed are explicitly rejected for these files.
Signed-off-by: Milosz Tanski <milosz@adfin.com>
[hch: rebased on top of my kiocb changes]
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Stephen Bates <stephen.bates@pmcs.com>
Tested-by: Stephen Bates <stephen.bates@pmcs.com>
Acked-by: Jeff Moyer <jmoyer@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
During testing, I discovered that __generic_file_splice_read() returns
0 (EOF) when aops->readpage fails with AOP_TRUNCATED_PAGE on the first
page of a single/multi-page splice read operation. This EOF return code
causes the userspace test to (correctly) report a zero-length read error
when it was expecting otherwise.
The current strategy of returning a partial non-zero read when ->readpage
returns AOP_TRUNCATED_PAGE works only when the failed page is not the
first of the lot being processed.
This patch attempts to retry lookup and call ->readpage again on pages
that had previously failed with AOP_TRUNCATED_PAGE. With this patch, my
tests pass and I haven't noticed any unwanted side effects.
This version removes the thrice-retry loop and instead indefinitely
retries lookups on AOP_TRUNCATED_PAGE errors from ->readpage. This
behavior is now similar to do_generic_file_read().
Signed-off-by: Abhi Das <adas@redhat.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Cc: Bob Peterson <rpeterso@redhat.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
The following test program from Dmitry can cause softlockups or RCU
stalls as it copies 1GB from tmpfs into eventfd and we don't have any
scheduling point at that path in sendfile(2) implementation:
int r1 = eventfd(0, 0);
int r2 = memfd_create("", 0);
unsigned long n = 1<<30;
fallocate(r2, 0, 0, n);
sendfile(r1, r2, 0, n);
Add cond_resched() into __splice_from_pipe() to fix the problem.
CC: Dmitry Vyukov <dvyukov@google.com>
CC: stable@vger.kernel.org
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Commit 296291cdd1 (mm: make sendfile(2) killable) fixed an issue where
sendfile(2) was doing a lot of tiny writes into a filesystem and thus
was unkillable for a long time. However sendfile(2) can be (mis)used to
issue lots of writes into arbitrary file descriptor such as evenfd or
similar special file descriptors which never hit the standard filesystem
write path and thus are still unkillable. E.g. the following example
from Dmitry burns CPU for ~16s on my test system without possibility to
be killed:
int r1 = eventfd(0, 0);
int r2 = memfd_create("", 0);
unsigned long n = 1<<30;
fallocate(r2, 0, 0, n);
sendfile(r1, r2, 0, n);
There are actually quite a few tests for pending signals in sendfile
code however we data to write is always available none of them seems to
trigger. So fix the problem by adding a test for pending signal into
splice_from_pipe_next() also before the loop waiting for pipe buffers to
be available. This should fix all the lockup issues with sendfile of the
do-ton-of-tiny-writes nature.
CC: stable@vger.kernel.org
Reported-by: Dmitry Vyukov <dvyukov@google.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
There are many places which use mapping_gfp_mask to restrict a more
generic gfp mask which would be used for allocations which are not
directly related to the page cache but they are performed in the same
context.
Let's introduce a helper function which makes the restriction explicit and
easier to track. This patch doesn't introduce any functional changes.
[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Michal Hocko <mhocko@suse.com>
Suggested-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Merge first patchbomb from Andrew Morton:
- a few misc things
- ocfs2 udpates
- kernel/watchdog.c feature work (took ages to get right)
- most of MM. A few tricky bits are held up and probably won't make 4.2.
* emailed patches from Andrew Morton <akpm@linux-foundation.org>: (91 commits)
mm: kmemleak_alloc_percpu() should follow the gfp from per_alloc()
mm, thp: respect MPOL_PREFERRED policy with non-local node
tmpfs: truncate prealloc blocks past i_size
mm/memory hotplug: print the last vmemmap region at the end of hot add memory
mm/mmap.c: optimization of do_mmap_pgoff function
mm: kmemleak: optimise kmemleak_lock acquiring during kmemleak_scan
mm: kmemleak: avoid deadlock on the kmemleak object insertion error path
mm: kmemleak: do not acquire scan_mutex in kmemleak_do_cleanup()
mm: kmemleak: fix delete_object_*() race when called on the same memory block
mm: kmemleak: allow safe memory scanning during kmemleak disabling
memcg: convert mem_cgroup->under_oom from atomic_t to int
memcg: remove unused mem_cgroup->oom_wakeups
frontswap: allow multiple backends
x86, mirror: x86 enabling - find mirrored memory ranges
mm/memblock: allocate boot time data structures from mirrored memory
mm/memblock: add extra "flags" to memblock to allow selection of memory based on attribute
mm: do not ignore mapping_gfp_mask in page cache allocation paths
mm/cma.c: fix typos in comments
mm/oom_kill.c: print points as unsigned int
mm/hugetlb: handle races in alloc_huge_page and hugetlb_reserve_pages
...
page_cache_read, do_generic_file_read, __generic_file_splice_read and
__ntfs_grab_cache_pages currently ignore mapping_gfp_mask when calling
add_to_page_cache_lru which might cause recursion into fs down in the
direct reclaim path if the mapping really relies on GFP_NOFS semantic.
This doesn't seem to be the case now because page_cache_read (page fault
path) doesn't seem to suffer from the reclaim recursion issues and
do_generic_file_read and __generic_file_splice_read also shouldn't be
called under fs locks which would deadlock in the reclaim path. Anyway it
is better to obey mapping gfp mask and prevent from later breakage.
[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Michal Hocko <mhocko@suse.cz>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Neil Brown <neilb@suse.de>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Rik van Riel <riel@redhat.com>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: Anton Altaparmakov <anton@tuxera.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
unix_stream_recvmsg is refactored to unix_stream_read_generic in this
patch and enhanced to deal with pipe splicing. The refactoring is
inneglible, we mostly have to deal with a non-existing struct msghdr
argument.
Signed-off-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
