Trond Myklebust reported soft lockups in XFS IO completion such as
this:
watchdog: BUG: soft lockup - CPU#12 stuck for 23s! [kworker/12:1:3106]
CPU: 12 PID: 3106 Comm: kworker/12:1 Not tainted 4.18.0-305.10.2.el8_4.x86_64 #1
Workqueue: xfs-conv/md127 xfs_end_io [xfs]
RIP: 0010:_raw_spin_unlock_irqrestore+0x11/0x20
Call Trace:
wake_up_page_bit+0x8a/0x110
iomap_finish_ioend+0xd7/0x1c0
iomap_finish_ioends+0x7f/0xb0
xfs_end_ioend+0x6b/0x100 [xfs]
xfs_end_io+0xb9/0xe0 [xfs]
process_one_work+0x1a7/0x360
worker_thread+0x1fa/0x390
kthread+0x116/0x130
ret_from_fork+0x35/0x40
Ioends are processed as an atomic completion unit when all the
chained bios in the ioend have completed their IO. Logically
contiguous ioends can also be merged and completed as a single,
larger unit. Both of these things can be problematic as both the
bio chains per ioend and the size of the merged ioends processed as
a single completion are both unbound.
If we have a large sequential dirty region in the page cache,
write_cache_pages() will keep feeding us sequential pages and we
will keep mapping them into ioends and bios until we get a dirty
page at a non-sequential file offset. These large sequential runs
can will result in bio and ioend chaining to optimise the io
patterns. The pages iunder writeback are pinned within these chains
until the submission chaining is broken, allowing the entire chain
to be completed. This can result in huge chains being processed
in IO completion context.
We get deep bio chaining if we have large contiguous physical
extents. We will keep adding pages to the current bio until it is
full, then we'll chain a new bio to keep adding pages for writeback.
Hence we can build bio chains that map millions of pages and tens of
gigabytes of RAM if the page cache contains big enough contiguous
dirty file regions. This long bio chain pins those pages until the
final bio in the chain completes and the ioend can iterate all the
chained bios and complete them.
OTOH, if we have a physically fragmented file, we end up submitting
one ioend per physical fragment that each have a small bio or bio
chain attached to them. We do not chain these at IO submission time,
but instead we chain them at completion time based on file
offset via iomap_ioend_try_merge(). Hence we can end up with unbound
ioend chains being built via completion merging.
XFS can then do COW remapping or unwritten extent conversion on that
merged chain, which involves walking an extent fragment at a time
and running a transaction to modify the physical extent information.
IOWs, we merge all the discontiguous ioends together into a
contiguous file range, only to then process them individually as
discontiguous extents.
This extent manipulation is computationally expensive and can run in
a tight loop, so merging logically contiguous but physically
discontigous ioends gains us nothing except for hiding the fact the
fact we broke the ioends up into individual physical extents at
submission and then need to loop over those individual physical
extents at completion.
Hence we need to have mechanisms to limit ioend sizes and
to break up completion processing of large merged ioend chains:
1. bio chains per ioend need to be bound in length. Pure overwrites
go straight to iomap_finish_ioend() in softirq context with the
exact bio chain attached to the ioend by submission. Hence the only
way to prevent long holdoffs here is to bound ioend submission
sizes because we can't reschedule in softirq context.
2. iomap_finish_ioends() has to handle unbound merged ioend chains
correctly. This relies on any one call to iomap_finish_ioend() being
bound in runtime so that cond_resched() can be issued regularly as
the long ioend chain is processed. i.e. this relies on mechanism #1
to limit individual ioend sizes to work correctly.
3. filesystems have to loop over the merged ioends to process
physical extent manipulations. This means they can loop internally,
and so we break merging at physical extent boundaries so the
filesystem can easily insert reschedule points between individual
extent manipulations.
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reported-and-tested-by: Trond Myklebust <trondmy@hammerspace.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
- Simplify the dax_operations API
- Eliminate bdev_dax_pgoff() in favor of the filesystem maintaining
and applying a partition offset to all its DAX iomap operations.
- Remove wrappers and device-mapper stacked callbacks for
->copy_from_iter() and ->copy_to_iter() in favor of moving
block_device relative offset responsibility to the
dax_direct_access() caller.
- Remove the need for an @bdev in filesystem-DAX infrastructure
- Remove unused uio helpers copy_from_iter_flushcache() and
copy_mc_to_iter() as only the non-check_copy_size() versions are
used for DAX.
- Prepare XFS for the pending (next merge window) DAX+reflink support
- Remove deprecated DEV_DAX_PMEM_COMPAT support
- Cleanup a straggling misuse of the GUID api
Tags offered after the branch was cut:
Reviewed-by: Mike Snitzer <snitzer@redhat.com>
Link: https://lore.kernel.org/r/Ydb/3P+8nvjCjYfO@redhat.com
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Merge tag 'libnvdimm-for-5.17' of git://git.kernel.org/pub/scm/linux/kernel/git/nvdimm/nvdimm
Pull dax and libnvdimm updates from Dan Williams:
"The bulk of this is a rework of the dax_operations API after
discovering the obstacles it posed to the work-in-progress DAX+reflink
support for XFS and other copy-on-write filesystem mechanics.
Primarily the need to plumb a block_device through the API to handle
partition offsets was a sticking point and Christoph untangled that
dependency in addition to other cleanups to make landing the
DAX+reflink support easier.
The DAX_PMEM_COMPAT option has been around for 4 years and not only
are distributions shipping userspace that understand the current
configuration API, but some are not even bothering to turn this option
on anymore, so it seems a good time to remove it per the deprecation
schedule. Recall that this was added after the device-dax subsystem
moved from /sys/class/dax to /sys/bus/dax for its sysfs organization.
All recent functionality depends on /sys/bus/dax.
Some other miscellaneous cleanups and reflink prep patches are
included as well.
Summary:
- Simplify the dax_operations API:
- Eliminate bdev_dax_pgoff() in favor of the filesystem
maintaining and applying a partition offset to all its DAX iomap
operations.
- Remove wrappers and device-mapper stacked callbacks for
->copy_from_iter() and ->copy_to_iter() in favor of moving
block_device relative offset responsibility to the
dax_direct_access() caller.
- Remove the need for an @bdev in filesystem-DAX infrastructure
- Remove unused uio helpers copy_from_iter_flushcache() and
copy_mc_to_iter() as only the non-check_copy_size() versions are
used for DAX.
- Prepare XFS for the pending (next merge window) DAX+reflink support
- Remove deprecated DEV_DAX_PMEM_COMPAT support
- Cleanup a straggling misuse of the GUID api"
* tag 'libnvdimm-for-5.17' of git://git.kernel.org/pub/scm/linux/kernel/git/nvdimm/nvdimm: (38 commits)
iomap: Fix error handling in iomap_zero_iter()
ACPI: NFIT: Import GUID before use
dax: remove the copy_from_iter and copy_to_iter methods
dax: remove the DAXDEV_F_SYNC flag
dax: simplify dax_synchronous and set_dax_synchronous
uio: remove copy_from_iter_flushcache() and copy_mc_to_iter()
iomap: turn the byte variable in iomap_zero_iter into a ssize_t
memremap: remove support for external pgmap refcounts
fsdax: don't require CONFIG_BLOCK
iomap: build the block based code conditionally
dax: fix up some of the block device related ifdefs
fsdax: shift partition offset handling into the file systems
dax: return the partition offset from fs_dax_get_by_bdev
iomap: add a IOMAP_DAX flag
xfs: pass the mapping flags to xfs_bmbt_to_iomap
xfs: use xfs_direct_write_iomap_ops for DAX zeroing
xfs: move dax device handling into xfs_{alloc,free}_buftarg
ext4: cleanup the dax handling in ext4_fill_super
ext2: cleanup the dax handling in ext2_fill_super
fsdax: decouple zeroing from the iomap buffered I/O code
...
This should be all that is needed for XFS to use large folios.
There is no code in this pull request to create large folios, but
no additional changes should be needed to XFS or iomap once they
are created.
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Merge tag 'iomap-5.17' of git://git.infradead.org/users/willy/linux
Pull iomap updates from Matthew Wilcox:
"Convert xfs/iomap to use folios.
This should be all that is needed for XFS to use large folios. There
is no code in this pull request to create large folios, but no
additional changes should be needed to XFS or iomap once they are
created.
Usually this would have come from Darrick, and we had intended that it
would come that route. Between the holidays and various things which
Darrick needed to work on, he asked if I could send things directly.
There weren't any other iomap patches pending for this release, which
probably also played a role"
* tag 'iomap-5.17' of git://git.infradead.org/users/willy/linux: (26 commits)
iomap: Inline __iomap_zero_iter into its caller
xfs: Support large folios
iomap: Support large folios in invalidatepage
iomap: Convert iomap_migrate_page() to use folios
iomap: Convert iomap_add_to_ioend() to take a folio
iomap: Simplify iomap_do_writepage()
iomap: Simplify iomap_writepage_map()
iomap,xfs: Convert ->discard_page to ->discard_folio
iomap: Convert iomap_write_end_inline to take a folio
iomap: Convert iomap_write_begin() and iomap_write_end() to folios
iomap: Convert __iomap_zero_iter to use a folio
iomap: Allow iomap_write_begin() to be called with the full length
iomap: Convert iomap_page_mkwrite to use a folio
iomap: Convert readahead and readpage to use a folio
iomap: Convert iomap_read_inline_data to take a folio
iomap: Use folio offsets instead of page offsets
iomap: Convert bio completions to use folios
iomap: Pass the iomap_page into iomap_set_range_uptodate
iomap: Add iomap_invalidate_folio
iomap: Convert iomap_releasepage to use a folio
...
iomap_write_end() does not return a negative errno to indicate an
error, but the number of bytes successfully copied. It cannot return
an error today, so include a debugging assertion like the one in
iomap_unshare_iter().
Fixes: c6f4046865 ("fsdax: decouple zeroing from the iomap buffered I/O code")
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20211221044450.517558-1-willy@infradead.org
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
To make the merge easier, replicate the inlining of __iomap_zero_iter()
into iomap_zero_iter() that is currently in the nvdimm tree.
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
If we're punching a hole in a large folio, we need to remove the
per-folio iomap data as the folio is about to be split and each page will
need its own. If a dirty folio is only partially-uptodate, the iomap
data contains the information about which blocks cannot be written back,
so assert that a dirty folio is fully uptodate.
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
The arguments are still pages for now, but we can use folios internally
and cut out a lot of calls to compound_head().
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
We still iterate one block at a time, but now we call compound_head()
less often.
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Rename end_offset to end_pos and offset_into_page to poff to match the
rest of the file. Simplify the handling of the last page straddling
i_size by doing the EOF check based on the byte granularity i_size
instead of converting to a pgoff prematurely.
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Rename end_offset to end_pos and file_offset to pos to match the rest
of the file. Simplify the loop by calculating nblocks up front instead
of each time around the loop.
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
XFS has the only implementation of ->discard_page today, so convert it
to use folios in the same patch as converting the API.
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
This conversion is only safe because iomap only supports writes to inline
data which starts at the beginning of the file.
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
These functions still only work in PAGE_SIZE chunks, but there are
fewer conversions from tail to head pages as a result of this patch.
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
The zero iterator can work in folio-sized chunks instead of page-sized
chunks. This will save a lot of page cache lookups if the file is cached
in large folios.
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
In the future, we want write_begin to know the entire length of the
write so that it can choose to allocate large folios. Pass the full
length in from __iomap_zero_iter() and limit it where necessary.
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
If we write to any page in a folio, we have to mark the entire
folio as dirty, and potentially COW the entire folio, because it'll
all get written back as one unit.
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Handle folios of arbitrary size instead of working in PAGE_SIZE units.
readahead_folio() decreases the page refcount for you, so this is not
quite a mechanical change.
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
We still only support up to a single page of inline data (at least,
per call to iomap_read_inline_data()), but it can now be written into
the middle of a folio in case we decide to allocate a 16KiB page for
a file that's 8.1KiB in size.
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Pass a folio around instead of the page, and make sure the offset
is relative to the start of the folio instead of the start of a page.
Also use size_t for offset & length to make it clear that these are byte
counts, and to support >2GB folios in the future.
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Use bio_for_each_folio() to iterate over each folio in the bio
instead of iterating over each page.
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
All but one caller already has the iomap_page, so we can avoid getting
it again.
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Keep iomap_invalidatepage around as a wrapper for use in address_space
operations.
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
This is an address_space operation, so its argument must remain as a
struct page, but we can use a folio internally.
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
iomap_page_release() was also assuming that it was being passed a
head page.
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
This function already assumed it was being passed a head page, so
just formalise that.
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
The big comment about only using a head page can go away now that
it takes a folio argument.
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
There are no plans to convert buffer_head infrastructure to use large
folios, but __block_write_begin_int() is called from iomap, and it's
more convenient and less error-prone if we pass in a folio from iomap.
It also has a nice saving of almost 200 bytes of code from removing
repeated calls to compound_head().
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
@bytes also holds the return value from iomap_write_end, which can
contain a negative error value. As @bytes is always less than the page
size even the signed type can hold the entire possible range.
Fixes: c6f4046865 ("fsdax: decouple zeroing from the iomap buffered I/O code")
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20211208091203.2927754-1-hch@lst.de
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Only build the block based iomap code if CONFIG_BLOCK is set. Currently
that is always the case, but it will change soon.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Dan Williams <dan.j.williams@intel.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Link: https://lore.kernel.org/r/20211129102203.2243509-29-hch@lst.de
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Unshare the DAX and iomap buffered I/O page zeroing code. This code
previously did a IS_DAX check deep inside the iomap code, which in
fact was the only DAX check in the code. Instead move these checks
into the callers. Most callers already have DAX special casing anyway
and XFS will need it for reflink support as well.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Dan Williams <dan.j.williams@intel.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Link: https://lore.kernel.org/r/20211129102203.2243509-19-hch@lst.de
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
No functional changes in this patch, just in preparation for efficiently
calling this light function from the block O_DIRECT handling.
Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Change iomap_read_inline_data to return 0 or an error code; this
simplifies the callers. Add a description.
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
[djwong: document the return value of iomap_read_inline_data explicitly]
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Before commit 740499c784 ("iomap: fix the iomap_readpage_actor return
value for inline data"), when hitting an IOMAP_INLINE extent,
iomap_readpage_actor would report having read the entire page. Since
then, it only reports having read the inline data (iomap->length).
This will force iomap_readpage into another iteration, and the
filesystem will report an unaligned hole after the IOMAP_INLINE extent.
But iomap_readpage_actor (now iomap_readpage_iter) isn't prepared to
deal with unaligned extents, it will get things wrong on filesystems
with a block size smaller than the page size, and we'll eventually run
into the following warning in iomap_iter_advance:
WARN_ON_ONCE(iter->processed > iomap_length(iter));
Fix that by changing iomap_readpage_iter to return 0 when hitting an
inline extent; this will cause iomap_iter to stop immediately.
To fix readahead as well, change iomap_readahead_iter to pass on
iomap_readpage_iter return values less than or equal to zero.
Fixes: 740499c784 ("iomap: fix the iomap_readpage_actor return value for inline data")
Cc: stable@vger.kernel.org # v5.15+
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Functions gfs2_file_read_iter and gfs2_file_write_iter are both
accessing the user buffer to write to or read from while holding the
inode glock. In the most basic scenario, that buffer will not be
resident and it will be mapped to the same file. Accessing the buffer
will trigger a page fault, and gfs2 will deadlock trying to take the
same inode glock again while trying to handle that fault.
Fix that and similar, more complex scenarios by disabling page faults
while accessing user buffers. To make this work, introduce a small
amount of new infrastructure and fix some bugs that didn't trigger so
far, with page faults enabled.
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Merge tag 'gfs2-v5.15-rc5-mmap-fault' of git://git.kernel.org/pub/scm/linux/kernel/git/gfs2/linux-gfs2
Pull gfs2 mmap + page fault deadlocks fixes from Andreas Gruenbacher:
"Functions gfs2_file_read_iter and gfs2_file_write_iter are both
accessing the user buffer to write to or read from while holding the
inode glock.
In the most basic deadlock scenario, that buffer will not be resident
and it will be mapped to the same file. Accessing the buffer will
trigger a page fault, and gfs2 will deadlock trying to take the same
inode glock again while trying to handle that fault.
Fix that and similar, more complex scenarios by disabling page faults
while accessing user buffers. To make this work, introduce a small
amount of new infrastructure and fix some bugs that didn't trigger so
far, with page faults enabled"
* tag 'gfs2-v5.15-rc5-mmap-fault' of git://git.kernel.org/pub/scm/linux/kernel/git/gfs2/linux-gfs2:
gfs2: Fix mmap + page fault deadlocks for direct I/O
iov_iter: Introduce nofault flag to disable page faults
gup: Introduce FOLL_NOFAULT flag to disable page faults
iomap: Add done_before argument to iomap_dio_rw
iomap: Support partial direct I/O on user copy failures
iomap: Fix iomap_dio_rw return value for user copies
gfs2: Fix mmap + page fault deadlocks for buffered I/O
gfs2: Eliminate ip->i_gh
gfs2: Move the inode glock locking to gfs2_file_buffered_write
gfs2: Introduce flag for glock holder auto-demotion
gfs2: Clean up function may_grant
gfs2: Add wrapper for iomap_file_buffered_write
iov_iter: Introduce fault_in_iov_iter_writeable
iov_iter: Turn iov_iter_fault_in_readable into fault_in_iov_iter_readable
gup: Turn fault_in_pages_{readable,writeable} into fault_in_{readable,writeable}
powerpc/kvm: Fix kvm_use_magic_page
iov_iter: Fix iov_iter_get_pages{,_alloc} page fault return value
The second argument was only used by the USB gadget code, yet everyone
pays the overhead of passing a zero to be passed into aio, where it
ends up being part of the aio res2 value.
Now that everybody is passing in zero, kill off the extra argument.
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Add a done_before argument to iomap_dio_rw that indicates how much of
the request has already been transferred. When the request succeeds, we
report that done_before additional bytes were tranferred. This is
useful for finishing a request asynchronously when part of the request
has already been completed synchronously.
We'll use that to allow iomap_dio_rw to be used with page faults
disabled: when a page fault occurs while submitting a request, we
synchronously complete the part of the request that has already been
submitted. The caller can then take care of the page fault and call
iomap_dio_rw again for the rest of the request, passing in the number of
bytes already tranferred.
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
In iomap_dio_rw, when iomap_apply returns an -EFAULT error and the
IOMAP_DIO_PARTIAL flag is set, complete the request synchronously and
return a partial result. This allows the caller to deal with the page
fault and retry the remainder of the request.
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
When a user copy fails in one of the helpers of iomap_dio_rw, fail with
-EFAULT instead of returning 0. This matches what iomap_dio_bio_actor
returns when it gets an -EFAULT from bio_iov_iter_get_pages. With these
changes, iomap_dio_actor now consistently fails with -EFAULT when a user
page cannot be faulted in.
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
struct io_comp_batch contains a list head and a completion handler, which
will allow completions to more effciently completed batches of IO.
For now, no functional changes in this patch, we just define the
io_comp_batch structure and add the argument to the file_operations iopoll
handler.
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Turn iov_iter_fault_in_readable into a function that returns the number
of bytes not faulted in, similar to copy_to_user, instead of returning a
non-zero value when any of the requested pages couldn't be faulted in.
This supports the existing users that require all pages to be faulted in
as well as new users that are happy if any pages can be faulted in.
Rename iov_iter_fault_in_readable to fault_in_iov_iter_readable to make
sure this change doesn't silently break things.
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
Replace the blk_poll interface that requires the caller to keep a queue
and cookie from the submissions with polling based on the bio.
Polling for the bio itself leads to a few advantages:
- the cookie construction can made entirely private in blk-mq.c
- the caller does not need to remember the request_queue and cookie
separately and thus sidesteps their lifetime issues
- keeping the device and the cookie inside the bio allows to trivially
support polling BIOs remapping by stacking drivers
- a lot of code to propagate the cookie back up the submission path can
be removed entirely.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Tested-by: Mark Wunderlich <mark.wunderlich@intel.com>
Link: https://lore.kernel.org/r/20211012111226.760968-15-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Switch the boolean spin argument to blk_poll to passing a set of flags
instead. This will allow to control polling behavior in a more fine
grained way.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Tested-by: Mark Wunderlich <mark.wunderlich@intel.com>
Link: https://lore.kernel.org/r/20211012111226.760968-10-hch@lst.de
[axboe: adapt to changed io_uring iopoll]
Signed-off-by: Jens Axboe <axboe@kernel.dk>
If an iocb is split into multiple bios we can't poll for both. So don't
bother to even try to poll in that case.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Tested-by: Mark Wunderlich <mark.wunderlich@intel.com>
Link: https://lore.kernel.org/r/20211012111226.760968-4-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Print all the offset, pos, and length quantities in hexadecimal. While
we're at it, update the types of the tracepoint structure fields to
match the types of the values being recorded in them.
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
When the max pages (last_page in the swap header + 1) is smaller than
the total pages (inode size) of the swapfile, iomap_swapfile_activate
overwrites sis->max with total pages.
However, frontswap_map is a swap page state bitmap allocated using the
initial sis->max page count read from the swap header. If swapfile
activation increases sis->max, it's possible for the frontswap code to
walk off the end of the bitmap, thereby corrupting kernel memory.
[djwong: modify the description a bit; the original paragraph reads:
"However, frontswap_map is allocated using max pages. When test and clear
the sis offset, which is larger than max pages, of frontswap_map in
__frontswap_invalidate_page(), neighbors of frontswap_map may be
overwritten, i.e., slab is polluted."
Note also that this bug resulted in a behavioral change: activating a
swap file that was formatted and later extended results in all pages
being activated, not the number of pages recorded in the swap header.]
This fixes the issue by considering the limitation of max pages of swap
info in iomap_swapfile_add_extent().
To reproduce the case, compile kernel with slub RED ZONE, then run test:
$ sudo stress-ng -a 1 -x softlockup,resources -t 72h --metrics --times \
--verify -v -Y /root/tmpdir/stress-ng/stress-statistic-12.yaml \
--log-file /root/tmpdir/stress-ng/stress-logfile-12.txt \
--temp-path /root/tmpdir/stress-ng/
We'll get the error log as below:
[ 1151.015141] =============================================================================
[ 1151.016489] BUG kmalloc-16 (Not tainted): Right Redzone overwritten
[ 1151.017486] -----------------------------------------------------------------------------
[ 1151.017486]
[ 1151.018997] Disabling lock debugging due to kernel taint
[ 1151.019873] INFO: 0x0000000084e43932-0x0000000098d17cae @offset=7392. First byte 0x0 instead of 0xcc
[ 1151.021303] INFO: Allocated in __do_sys_swapon+0xcf6/0x1170 age=43417 cpu=9 pid=3816
[ 1151.022538] __slab_alloc+0xe/0x20
[ 1151.023069] __kmalloc_node+0xfd/0x4b0
[ 1151.023704] __do_sys_swapon+0xcf6/0x1170
[ 1151.024346] do_syscall_64+0x33/0x40
[ 1151.024925] entry_SYSCALL_64_after_hwframe+0x44/0xa9
[ 1151.025749] INFO: Freed in put_cred_rcu+0xa1/0xc0 age=43424 cpu=3 pid=2041
[ 1151.026889] kfree+0x276/0x2b0
[ 1151.027405] put_cred_rcu+0xa1/0xc0
[ 1151.027949] rcu_do_batch+0x17d/0x410
[ 1151.028566] rcu_core+0x14e/0x2b0
[ 1151.029084] __do_softirq+0x101/0x29e
[ 1151.029645] asm_call_irq_on_stack+0x12/0x20
[ 1151.030381] do_softirq_own_stack+0x37/0x40
[ 1151.031037] do_softirq.part.15+0x2b/0x30
[ 1151.031710] __local_bh_enable_ip+0x4b/0x50
[ 1151.032412] copy_fpstate_to_sigframe+0x111/0x360
[ 1151.033197] __setup_rt_frame+0xce/0x480
[ 1151.033809] arch_do_signal+0x1a3/0x250
[ 1151.034463] exit_to_user_mode_prepare+0xcf/0x110
[ 1151.035242] syscall_exit_to_user_mode+0x27/0x190
[ 1151.035970] entry_SYSCALL_64_after_hwframe+0x44/0xa9
[ 1151.036795] INFO: Slab 0x000000003b9de4dc objects=44 used=9 fp=0x00000000539e349e flags=0xfffffc0010201
[ 1151.038323] INFO: Object 0x000000004855ba01 @offset=7376 fp=0x0000000000000000
[ 1151.038323]
[ 1151.039683] Redzone 000000008d0afd3d: cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc ................
[ 1151.041180] Object 000000004855ba01: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
[ 1151.042714] Redzone 0000000084e43932: 00 00 00 c0 cc cc cc cc ........
[ 1151.044120] Padding 000000000864c042: 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a ZZZZZZZZZZZZZZZZ
[ 1151.045615] CPU: 5 PID: 3816 Comm: stress-ng Tainted: G B 5.10.50+ #7
[ 1151.046846] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.12.1-0-ga5cab58e9a3f-prebuilt.qemu.org 04/01/2014
[ 1151.048633] Call Trace:
[ 1151.049072] dump_stack+0x57/0x6a
[ 1151.049585] check_bytes_and_report+0xed/0x110
[ 1151.050320] check_object+0x1eb/0x290
[ 1151.050924] ? __x64_sys_swapoff+0x39a/0x540
[ 1151.051646] free_debug_processing+0x151/0x350
[ 1151.052333] __slab_free+0x21a/0x3a0
[ 1151.052938] ? _cond_resched+0x2d/0x40
[ 1151.053529] ? __vunmap+0x1de/0x220
[ 1151.054139] ? __x64_sys_swapoff+0x39a/0x540
[ 1151.054796] ? kfree+0x276/0x2b0
[ 1151.055307] kfree+0x276/0x2b0
[ 1151.055832] __x64_sys_swapoff+0x39a/0x540
[ 1151.056466] do_syscall_64+0x33/0x40
[ 1151.057084] entry_SYSCALL_64_after_hwframe+0x44/0xa9
[ 1151.057866] RIP: 0033:0x150340b0ffb7
[ 1151.058481] Code: Unable to access opcode bytes at RIP 0x150340b0ff8d.
[ 1151.059537] RSP: 002b:00007fff7f4ee238 EFLAGS: 00000246 ORIG_RAX: 00000000000000a8
[ 1151.060768] RAX: ffffffffffffffda RBX: 00007fff7f4ee66c RCX: 0000150340b0ffb7
[ 1151.061904] RDX: 000000000000000a RSI: 0000000000018094 RDI: 00007fff7f4ee860
[ 1151.063033] RBP: 00007fff7f4ef980 R08: 0000000000000000 R09: 0000150340a672bd
[ 1151.064135] R10: 00007fff7f4edca0 R11: 0000000000000246 R12: 0000000000018094
[ 1151.065253] R13: 0000000000000005 R14: 000000000160d930 R15: 00007fff7f4ee66c
[ 1151.066413] FIX kmalloc-16: Restoring 0x0000000084e43932-0x0000000098d17cae=0xcc
[ 1151.066413]
[ 1151.067890] FIX kmalloc-16: Object at 0x000000004855ba01 not freed
Fixes: 67482129cd ("iomap: add a swapfile activation function")
Fixes: a45c0eccc5 ("iomap: move the swapfile code into a separate file")
Signed-off-by: Gang Deng <gavin.dg@linux.alibaba.com>
Signed-off-by: Xu Yu <xuyu@linux.alibaba.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Now that we've moved iomap to the iterator model, rename this file to be
in sync with the functions contained inside of it.
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
The srcmap returned from iomap_iter_srcmap is never modified, so mark
the iomap returned from it const and constify a lot of code that never
modifies the iomap.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Instead of another internal flags namespace inside of buffered-io.c,
just pass a UNSHARE hint in the main iomap flags field.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Pass the iomap_iter structure instead of individual parameters to
various internal helpers for buffered I/O.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
iomap_apply is unused now, so remove it.
Signed-off-by: Christoph Hellwig <hch@lst.de>
[djwong: rebase this patch to preserve git history of iomap loop control]
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Dave Chinner
Linus Torvalds
Matthew Wilcox (Oracle)
Christoph Hellwig
Jens Axboe
Andreas Gruenbacher
Darrick J. Wong
Xu Yu