Print a useful warning instead.
Reported-by: NFinn Thain <fthain@telegraphics.com.au>
Tested-by: NFinn Thain <fthain@telegraphics.com.au>
Signed-off-by: NChristoph Hellwig <hch@lst.de>

Various PCI bridges (VIA PCI, Xilinx PCIe) limit DMA to only 32-bits
even if the device itself supports more.  Add a single bit flag to
struct device (to be moved into the dma extension once we get to it)
to flag such devices and reject larger DMA to them.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Reviewed-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

If the radix tree underlying the IDR happens to be full and we attempt
to remove an id which is larger than any id in the IDR, we will call
__radix_tree_delete() with an uninitialised 'slot' pointer, at which
point anything could happen.  This was easiest to hit with a single
entry at id 0 and attempting to remove a non-0 id, but it could have
happened with 64 entries and attempting to remove an id >= 64.

Roman said:

  The syzcaller test boils down to opening /dev/kvm, creating an
  eventfd, and calling a couple of KVM ioctls. None of this requires
  superuser. And the result is dereferencing an uninitialized pointer
  which is likely a crash. The specific path caught by syzbot is via
  KVM_HYPERV_EVENTD ioctl which is new in 4.17. But I guess there are
  other user-triggerable paths, so cc:stable is probably justified.

Matthew added:

  We have around 250 calls to idr_remove() in the kernel today. Many of
  them pass an ID which is embedded in the object they're removing, so
  they're safe. Picking a few likely candidates:

  drivers/firewire/core-cdev.c looks unsafe; the ID comes from an ioctl.
  drivers/gpu/drm/amd/amdgpu/amdgpu_ctx.c is similar
  drivers/atm/nicstar.c could be taken down by a handcrafted packet

Link: http://lkml.kernel.org/r/20180518175025.GD6361@bombadil.infradead.org
Fixes: 0a835c4f ("Reimplement IDR and IDA using the radix tree")
Reported-by: <syzbot+35666cba7f0a337e2e79@syzkaller.appspotmail.com>
Debugged-by: NRoman Kagan <rkagan@virtuozzo.com>
Signed-off-by: NMatthew Wilcox <mawilcox@microsoft.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

When the allocation process is scheduled back and the mapped hw queue is
changed, fake one extra wake up on previous queue for compensating wake
up miss, so other allocations on the previous queue won't be starved.

This patch fixes one request allocation hang issue, which can be
triggered easily in case of very low nr_request.

The race is as follows:

1) 2 hw queues, nr_requests are 2, and wake_batch is one

2) there are 3 waiters on hw queue 0

3) two in-flight requests in hw queue 0 are completed, and only two
   waiters of 3 are waken up because of wake_batch, but both the two
   waiters can be scheduled to another CPU and cause to switch to hw
   queue 1

4) then the 3rd waiter will wait for ever, since no in-flight request
   is in hw queue 0 any more.

5) this patch fixes it by the fake wakeup when waiter is scheduled to
   another hw queue

Cc: <stable@vger.kernel.org>
Reviewed-by: NOmar Sandoval <osandov@fb.com>
Signed-off-by: NMing Lei <ming.lei@redhat.com>

Modified commit message to make it clearer, and make it apply on
top of the 4.18 branch.
Signed-off-by: NJens Axboe <axboe@kernel.dk>

Drivers/subsystems creating scatterlists for DMA should be taking care
to respect the scatter-gather limitations of the appropriate device, as
described by dma_parms. A DMA API implementation cannot feasibly split
a scatterlist into *more* entries than originally passed, so it is not
well defined what they should do when given a segment larger than the
limit they are also required to respect.

Conversely, devices which are less limited than the rather conservative
defaults, or indeed have no limitations at all (e.g. GPUs with their own
internal MMU), should be encouraged to set appropriate dma_parms, as
they may get more efficient DMA mapping performance out of it.
Signed-off-by: NRobin Murphy <robin.murphy@arm.com>
Signed-off-by: NChristoph Hellwig <hch@lst.de>

Add a new dma_map_ops implementation that uses dma-direct for the
address mapping of streaming mappings, and which requires arch-specific
implemenations of coherent allocate/free.

Architectures have to provide flushing helpers to ownership trasnfers
to the device and/or CPU, and can provide optional implementations of
the coherent mmap functionality, and the cache_flush routines for
non-coherent long term allocations.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Tested-by: NAlexey Brodkin <abrodkin@synopsys.com>
Acked-by: NVineet Gupta <vgupta@synopsys.com>

ARCH_DMA_ADDR_T_64BIT is always true for 64-bit architectures now, so we
can skip the clause requiring it.  'n' is the default default, so no need
to explicitly state it.
Tested-by: NAlexey Brodkin <abrodkin@synopsys.com>
Acked-by: NVineet Gupta <vgupta@synopsys.com>
Signed-off-by: NChristoph Hellwig <hch@lst.de>

Fix a race in the multi-order iteration code which causes the kernel to
hit a GP fault.  This was first seen with a production v4.15 based
kernel (4.15.6-300.fc27.x86_64) utilizing a DAX workload which used
order 9 PMD DAX entries.

The race has to do with how we tear down multi-order sibling entries
when we are removing an item from the tree.  Remember for example that
an order 2 entry looks like this:

  struct radix_tree_node.slots[] = [entry][sibling][sibling][sibling]

where 'entry' is in some slot in the struct radix_tree_node, and the
three slots following 'entry' contain sibling pointers which point back
to 'entry.'

When we delete 'entry' from the tree, we call :

  radix_tree_delete()
    radix_tree_delete_item()
      __radix_tree_delete()
        replace_slot()

replace_slot() first removes the siblings in order from the first to the
last, then at then replaces 'entry' with NULL.  This means that for a
brief period of time we end up with one or more of the siblings removed,
so:

  struct radix_tree_node.slots[] = [entry][NULL][sibling][sibling]

This causes an issue if you have a reader iterating over the slots in
the tree via radix_tree_for_each_slot() while only under
rcu_read_lock()/rcu_read_unlock() protection.  This is a common case in
mm/filemap.c.

The issue is that when __radix_tree_next_slot() => skip_siblings() tries
to skip over the sibling entries in the slots, it currently does so with
an exact match on the slot directly preceding our current slot.
Normally this works:

                                      V preceding slot
  struct radix_tree_node.slots[] = [entry][sibling][sibling][sibling]
                                              ^ current slot

This lets you find the first sibling, and you skip them all in order.

But in the case where one of the siblings is NULL, that slot is skipped
and then our sibling detection is interrupted:

                                             V preceding slot
  struct radix_tree_node.slots[] = [entry][NULL][sibling][sibling]
                                                    ^ current slot

This means that the sibling pointers aren't recognized since they point
all the way back to 'entry', so we think that they are normal internal
radix tree pointers.  This causes us to think we need to walk down to a
struct radix_tree_node starting at the address of 'entry'.

In a real running kernel this will crash the thread with a GP fault when
you try and dereference the slots in your broken node starting at
'entry'.

We fix this race by fixing the way that skip_siblings() detects sibling
nodes.  Instead of testing against the preceding slot we instead look
for siblings via is_sibling_entry() which compares against the position
of the struct radix_tree_node.slots[] array.  This ensures that sibling
entries are properly identified, even if they are no longer contiguous
with the 'entry' they point to.

Link: http://lkml.kernel.org/r/20180503192430.7582-6-ross.zwisler@linux.intel.com
Fixes: 148deab2 ("radix-tree: improve multiorder iterators")
Signed-off-by: NRoss Zwisler <ross.zwisler@linux.intel.com>
Reported-by: NCR, Sapthagirish <sapthagirish.cr@intel.com>
Reviewed-by: NJan Kara <jack@suse.cz>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Dave Chinner <david@fromorbit.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

I had neglected to increment the error counter when the tests failed,
which made the tests noisy when they fail, but not actually return an
error code.

Link: http://lkml.kernel.org/r/20180509114328.9887-1-mpe@ellerman.id.au
Fixes: 3cc78125 ("lib/test_bitmap.c: add optimisation tests")
Signed-off-by: NMatthew Wilcox <mawilcox@microsoft.com>
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>
Reported-by: NMichael Ellerman <mpe@ellerman.id.au>
Tested-by: NMichael Ellerman <mpe@ellerman.id.au>
Reviewed-by: NKees Cook <keescook@chromium.org>
Cc: Yury Norov <ynorov@caviumnetworks.com>
Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: <stable@vger.kernel.org>	[4.13+]
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Reviewing Tobin's patches for getting pointers out early before
entropy has been established, I noticed that there's a lone smp_mb() in
the code. As with most lone memory barriers, this one appears to be
incorrectly used.

We currently basically have this:

	get_random_bytes(&ptr_key, sizeof(ptr_key));
	/*
	 * have_filled_random_ptr_key==true is dependent on get_random_bytes().
	 * ptr_to_id() needs to see have_filled_random_ptr_key==true
	 * after get_random_bytes() returns.
	 */
	smp_mb();
	WRITE_ONCE(have_filled_random_ptr_key, true);

And later we have:

	if (unlikely(!have_filled_random_ptr_key))
		return string(buf, end, "(ptrval)", spec);

/* Missing memory barrier here. */

	hashval = (unsigned long)siphash_1u64((u64)ptr, &ptr_key);

As the CPU can perform speculative loads, we could have a situation
with the following:

	CPU0				CPU1
	----				----
				   load ptr_key = 0
   store ptr_key = random
   smp_mb()
   store have_filled_random_ptr_key

				   load have_filled_random_ptr_key = true

				    BAD BAD BAD! (you're so bad!)

Because nothing prevents CPU1 from loading ptr_key before loading
have_filled_random_ptr_key.

But this race is very unlikely, but we can't keep an incorrect smp_mb() in
place. Instead, replace the have_filled_random_ptr_key with a static_branch
not_filled_random_ptr_key, that is initialized to true and changed to false
when we get enough entropy. If the update happens in early boot, the
static_key is updated immediately, otherwise it will have to wait till
entropy is filled and this happens in an interrupt handler which can't
enable a static_key, as that requires a preemptible context. In that case, a
work_queue is used to enable it, as entropy already took too long to
establish in the first place waiting a little more shouldn't hurt anything.

The benefit of using the static key is that the unlikely branch in
vsprintf() now becomes a nop.

Link: http://lkml.kernel.org/r/20180515100558.21df515e@gandalf.local.home

Cc: stable@vger.kernel.org
Fixes: ad67b74d ("printk: hash addresses printed with %p")
Acked-by: NLinus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: NSteven Rostedt (VMware) <rostedt@goodmis.org>

Use the updated memcpy_mcsafe() implementation to define
copy_user_mcsafe() and copy_to_iter_mcsafe(). The most significant
difference from typical copy_to_iter() is that the ITER_KVEC and
ITER_BVEC iterator types can fail to complete a full transfer.
Signed-off-by: NDan Williams <dan.j.williams@intel.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tony Luck <tony.luck@intel.com>
Cc: hch@lst.de
Cc: linux-fsdevel@vger.kernel.org
Cc: linux-nvdimm@lists.01.org
Link: http://lkml.kernel.org/r/152539239150.31796.9189779163576449784.stgit@dwillia2-desk3.amr.corp.intel.comSigned-off-by: NIngo Molnar <mingo@kernel.org>

If we have multiple callers of sbq_wake_up(), we can end up in a
situation where the wait_cnt will continually go more and more
negative. Consider the case where our wake batch is 1, hence
wait_cnt will start out as 1.

wait_cnt == 1

CPU0				CPU1
atomic_dec_return(), cnt == 0
				atomic_dec_return(), cnt == -1
				cmpxchg(-1, 0) (succeeds)
				[wait_cnt now 0]
cmpxchg(0, 1) (fails)

This ends up with wait_cnt being 0, we'll wakeup immediately
next time. Going through the same loop as above again, and
we'll have wait_cnt -1.

For the case where we have a larger wake batch, the only
difference is that the starting point will be higher. We'll
still end up with continually smaller batch wakeups, which
defeats the purpose of the rolling wakeups.

Always reset the wait_cnt to the batch value. Then it doesn't
matter who wins the race. But ensure that whomever does win
the race is the one that increments the ws index and wakes up
our batch count, loser gets to call __sbq_wake_up() again to
account his wakeups towards the next active wait state index.

Fixes: 6c0ca7ae ("sbitmap: fix wakeup hang after sbq resize")
Reviewed-by: NOmar Sandoval <osandov@fb.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

If DMA_ATTR_NO_WARN is passed to swiotlb_alloc_buffer(), it should be
passed further down to swiotlb_tbl_map_single(). Otherwise we escape
half of the warnings but still log the other half.

This is one of the multiple causes of spurious warnings reported at:
https://bugs.freedesktop.org/show_bug.cgi?id=104082Signed-off-by: NJean Delvare <jdelvare@suse.de>
Fixes: 0176adb0 ("swiotlb: refactor coherent buffer allocation")
Cc: Christoph Hellwig <hch@lst.de>
Cc: Christian König <christian.koenig@amd.com>
Cc: Michel Dänzer <michel@daenzer.net>
Cc: Takashi Iwai <tiwai@suse.de>
Cc: stable@vger.kernel.org # v4.16

test_find_first_bit() is intentionally sub-optimal, and may cause soft
lockup due to long time of run on some systems.  So decrease length of
bitmap to traverse to avoid lockup.

With the change below, time of test execution doesn't exceed 0.2 seconds
on my testing system.

Link: http://lkml.kernel.org/r/20180420171949.15710-1-ynorov@caviumnetworks.com
Fixes: 4441fca0 ("lib: test module for find_*_bit() functions")
Signed-off-by: NYury Norov <ynorov@caviumnetworks.com>
Reviewed-by: NAndrew Morton <akpm@linux-foundation.org>
Reported-by: NFengguang Wu <fengguang.wu@intel.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Make sure the user passed the right value to
sbitmap_queue_min_shallow_depth().
Acked-by: NPaolo Valente <paolo.valente@linaro.org>
Signed-off-by: NOmar Sandoval <osandov@fb.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

The sbitmap queue wake batch is calculated such that once allocations
start blocking, all of the bits which are already allocated must be
enough to fulfill the batch counters of all of the waitqueues. However,
the shallow allocation depth can break this invariant, since we block
before our full depth is being utilized. Add
sbitmap_queue_min_shallow_depth(), which saves the minimum shallow depth
the sbq will use, and update sbq_calc_wake_batch() to take it into
account.
Acked-by: NPaolo Valente <paolo.valente@linaro.org>
Signed-off-by: NOmar Sandoval <osandov@fb.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

swiotlb use physical address of bounce buffer when do map and unmap,
therefore, related comment should be updated.
Signed-off-by: NYisheng Xie <xieyisheng1@huawei.com>
Signed-off-by: NChristoph Hellwig <hch@lst.de>

swiotlb now selects the DMA_DIRECT_OPS config symbol, so this will
always be true.
Signed-off-by: NChristoph Hellwig <hch@lst.de>

This way we have one central definition of it, and user can select it as
needed.  The new option is not user visible, which is the behavior
it had in most architectures, with a few notable exceptions:

 - On x86_64 and mips/loongson3 it used to be user selectable, but
   defaulted to y.  It now is unconditional, which seems like the right
   thing for 64-bit architectures without guaranteed availablity of
   IOMMUs.
 - on powerpc the symbol is user selectable and defaults to n, but
   many boards select it.  This change assumes no working setup
   required a manual selection, but if that turned out to be wrong
   we'll have to add another select statement or two for the respective
   boards.
Signed-off-by: NChristoph Hellwig <hch@lst.de>

Define this symbol if the architecture either uses 64-bit pointers or the
PHYS_ADDR_T_64BIT is set.  This covers 95% of the old arch magic.  We only
need an additional select for Xen on ARM (why anyway?), and we now always
set ARCH_DMA_ADDR_T_64BIT on mips boards with 64-bit physical addressing
instead of only doing it when highmem is set.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Acked-by: NJames Hogan <jhogan@kernel.org>

This way we have one central definition of it, and user can select it as
needed.  Note that we now also always select it when CONFIG_DMA_API_DEBUG
is select, which fixes some incorrect checks in a few network drivers.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Reviewed-by: NAnshuman Khandual <khandual@linux.vnet.ibm.com>

This way we have one central definition of it, and user can select it as
needed.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Reviewed-by: NAnshuman Khandual <khandual@linux.vnet.ibm.com>

This way we have one central definition of it, and user can select it as
needed.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Reviewed-by: NAnshuman Khandual <khandual@linux.vnet.ibm.com>

This avoids selecting IOMMU_HELPER just for this function.  And we only
use it once or twice in normal builds so this often even is a size
reduction.
Signed-off-by: NChristoph Hellwig <hch@lst.de>

This function is only used by built-in code.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Reviewed-by: NAnshuman Khandual <khandual@linux.vnet.ibm.com>

This code is only used by sparc, and all new iommu drivers should use the
drivers/iommu/ framework.  Also remove the unused exports.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Acked-by: NDavid S. Miller <davem@davemloft.net>
Reviewed-by: NAnshuman Khandual <khandual@linux.vnet.ibm.com>

There is no arch specific code required for dma-debug, so there is no
need to opt into the support either.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Reviewed-by: NRobin Murphy <robin.murphy@arm.com>

Only used by the AMD GART and Intel VT-D drivers, which must be built in.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Reviewed-by: NRobin Murphy <robin.murphy@arm.com>

Just keep a single variable with a descriptive name instead of two
with confusing names.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Reviewed-by: NRobin Murphy <robin.murphy@arm.com>

Most mainstream architectures are using 65536 entries, so lets stick to
that.  If someone is really desperate to override it that can still be
done through <asm/dma-mapping.h>, but I'd rather see a really good
rationale for that.

dma_debug_init is now called as a core_initcall, which for many
architectures means much earlier, and provides dma-debug functionality
earlier in the boot process.  This should be safe as it only relies
on the memory allocator already being available.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Acked-by: NMarek Szyprowski <m.szyprowski@samsung.com>
Reviewed-by: NRobin Murphy <robin.murphy@arm.com>

This was used by the ide, scsi and networking code in the past to
determine if they should bounce payloads.  Now that the dma mapping
always have to support dma to all physical memory (thanks to swiotlb
for non-iommu systems) there is no need to this crude hack any more.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Acked-by: Palmer Dabbelt <palmer@sifive.com> (for riscv)
Reviewed-by: NJens Axboe <axboe@kernel.dk>

As the recent swiotlb bug revealed, we seem to have given up the direct
DMA allocation too early and felt back to swiotlb allocation.  The reason
is that swiotlb allocator expected that dma_direct_alloc() would try
harder to get pages even below 64bit DMA mask with GFP_DMA32, but the
function doesn't do that but only deals with GFP_DMA case.

This patch adds a similar fallback reallocation with GFP_DMA32 as we've
done with GFP_DMA.  The condition is that the coherent mask is smaller
than 64bit (i.e. some address limitation), and neither GFP_DMA nor
GFP_DMA32 is set beforehand.
Signed-off-by: NTakashi Iwai <tiwai@suse.de>
Signed-off-by: NChristoph Hellwig <hch@lst.de>

Smatch complains here:

    lib/swiotlb.c:730 swiotlb_alloc_buffer()
    warn: variable dereferenced before check 'dev' (see line 716)

"dev" isn't ever NULL in this function so we can just remove the check.
Signed-off-by: NDan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: NChristoph Hellwig <hch@lst.de>

Make n signed to avoid leaking the pages array if __pipe_get_pages()
fails to allocate any pages.
Signed-off-by: NIlya Dryomov <idryomov@gmail.com>
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

It returns -EFAULT and happens to be a helper for pipe_get_pages()
whose return type is ssize_t.
Signed-off-by: NIlya Dryomov <idryomov@gmail.com>
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

The result was printing the warning only when we were explicitly asked
not to.

Cc: stable@vger.kernel.org
Fixes: 0176adb0 "swiotlb: refactor
 coherent buffer allocation"
Signed-off-by: NMichel Dänzer <michel.daenzer@amd.com>
Reviewed-by: Christian König <christian.koenig@amd.com>.
Signed-off-by: NChristoph Hellwig <hch@lst.de>

The errseq_t infrastructure assumes that errors which occurred before
the file descriptor was opened are of no interest to the application.
This turns out to be a regression for some applications, notably Postgres.

Before errseq_t, a writeback error would be reported exactly once (as
long as the inode remained in memory), so Postgres could open a file,
call fsync() and find out whether there had been a writeback error on
that file from another process.

This patch changes the errseq infrastructure to report errors to all
file descriptors which are opened after the error occurred, but before
it was reported to any file descriptor.  This restores the user-visible
behaviour.

Cc: stable@vger.kernel.org
Fixes: 5660e13d ("fs: new infrastructure for writeback error handling and reporting")
Signed-off-by: NMatthew Wilcox <mawilcox@microsoft.com>
Reviewed-by: NJeff Layton <jlayton@kernel.org>
Signed-off-by: NJeff Layton <jlayton@redhat.com>

When an allocation with lower dma_coherent mask fails, dma_direct_alloc()
retries the allocation with GFP_DMA.  But, this is useless for
architectures that hav no ZONE_DMA.

Fix it by adding the check of CONFIG_ZONE_DMA before retrying the
allocation.

Fixes: 95f18391 ("dma-direct: retry allocations using GFP_DMA for small masks")
Signed-off-by: NTakashi Iwai <tiwai@suse.de>
Signed-off-by: NChristoph Hellwig <hch@lst.de>

This WARNING proved to be noisy. The function still returns an error
and callers should handle it. That's how most of kernel code works.
Downgrade the WARNING to pr_err() and leave WARNINGs for kernel bugs.
Signed-off-by: NDmitry Vyukov <dvyukov@google.com>
Reported-by: syzbot+209c0f67f99fec8eb14b@syzkaller.appspotmail.com
Reported-by: syzbot+7fb6d9525a4528104e05@syzkaller.appspotmail.com
Reported-by: syzbot+2e63711063e2d8f9ea27@syzkaller.appspotmail.com
Reported-by: syzbot+de73361ee4971b6e6f75@syzkaller.appspotmail.com
Cc: stable <stable@vger.kernel.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Make lib/textsearch.c usable as kernel-doc.
Add textsearch() function family to kernel-api documentation.
Fix kernel-doc warnings in <linux/textsearch.h>:
  ../include/linux/textsearch.h:65: warning: Incorrect use of kernel-doc format:
	* get_next_block - fetch next block of data
  ../include/linux/textsearch.h:82: warning: Incorrect use of kernel-doc format:
	* finish - finalize/clean a series of get_next_block() calls
Signed-off-by: NRandy Dunlap <rdunlap@infradead.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>