- 01 Sep, 2017 23 commits
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Christoph Hellwig authored
This avoids poking into the internals of the extent list. Also return the number of extents as the return value instead of an additional by reference argument, and make it available to callers outside of xfs_bmap_util.c Signed-off-by:
Christoph Hellwig <hch@lst.de> Reviewed-by:
Darrick J. Wong <darrick.wong@oracle.com> Signed-off-by:
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Christoph Hellwig authored
This abstracts the function away from details of the low-level extent list implementation. Signed-off-by:
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Christoph Hellwig authored
This abstracts the function away from details of the low-level extent list implementation. Note that it seems like the previous implementation of rmap for the merge case was completely broken, but it no seems appear to trigger that. Signed-off-by:
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Christoph Hellwig authored
For the first right move we need to look up next_fsb. That means our last fsb that contains next_fsb must also be the current extent, so take advantage of that by moving the code around a bit. Signed-off-by:
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Christoph Hellwig authored
Use the bmap abstraction instead of open-coding bmbt details here. Signed-off-by:
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Christoph Hellwig authored
Use the helper instead of open coding it, to provide a better abstraction for the scalable extent list work. This also gets an additional assert and trace point for free. Signed-off-by:
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Christoph Hellwig authored
This helper is used to update an extent record based on the extent index, and can be used to provide a level of abstractions between callers that want to modify in-core extent records and the details of the extent list implementation. Also switch all users of the xfs_bmbt_set_all(xfs_iext_get_ext(...)) pattern to this new helper. Signed-off-by:
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Christoph Hellwig authored
Add a new __xfs_filemap_fault helper that implements all four page fault callouts, and make these methods themselves small stubs that set the correct write_fault flag, and exit early for the non-DAX case for the hugepage related ones. Also remove the extra size checking in the pfn_fault path, which is now handled in the core DAX code. Life would be so much simpler if we only had one method for all this. Signed-off-by:
Ross Zwisler <ross.zwisler@linux.intel.com> Reviewed-by:
Jan Kara <jack@suse.cz> Reviewed-by:
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Christoph Hellwig authored
All callers will need the VM_FAULT_* flags, so convert in the helper. Signed-off-by:
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Brian Foster authored
The owner change bmbt scan that occurs during extent swap operations does not handle ordered buffer failures. Buffers that cannot be marked ordered must be physically logged so previously dirty ranges of the buffer can be relogged in the transaction. Since the bmbt scan may need to process and potentially log a large number of blocks, we can't expect to complete this operation in a single transaction. Update extent swap to use a permanent transaction with enough log reservation to physically log a buffer. Update the bmbt scan to physically log any buffers that cannot be ordered and to terminate the scan with -EAGAIN. On -EAGAIN, the caller rolls the transaction and restarts the scan. Finally, update the bmbt scan helper function to skip bmbt blocks that already match the expected owner so they are not reprocessed after scan restarts. Signed-off-by:
Brian Foster <bfoster@redhat.com> Reviewed-by:
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Brian Foster authored
Ordered buffers are used in situations where the buffer is not physically logged but must pass through the transaction/logging pipeline for a particular transaction. As a result, ordered buffers are not unpinned and written back until the transaction commits to the log. Ordered buffers have a strict requirement that the target buffer must not be currently dirty and resident in the log pipeline at the time it is marked ordered. If a dirty+ordered buffer is committed, the buffer is reinserted to the AIL but not physically relogged at the LSN of the associated checkpoint. The buffer log item is assigned the LSN of the latest checkpoint and the AIL effectively releases the previously logged buffer content from the active log before the buffer has been written back. If the tail pushes forward and a filesystem crash occurs while in this state, an inconsistent filesystem could result. It is currently the caller responsibility to ensure an ordered buffer is not already dirty from a previous modification. This is unclear and error prone when not used in situations where it is guaranteed a buffer has not been previously modified (such as new metadata allocations). To facilitate general purpose use of ordered buffers, update xfs_trans_ordered_buf() to conditionally order the buffer based on state of the log item and return the status of the result. If the bli is dirty, do not order the buffer and return false. The caller must either physically log the buffer (having acquired the appropriate log reservation) or push it from the AIL to clean it before it can be marked ordered in the current transaction. Note that ordered buffers are currently only used in two situations: 1.) inode chunk allocation where previously logged buffers are not possible and 2.) extent swap which will be updated to handle ordered buffer failures in a separate patch. Signed-off-by:
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Brian Foster authored
The extent swap operation currently resets bmbt block owners before the inode forks are swapped. The bmbt buffers are marked as ordered so they do not have to be physically logged in the transaction. This use of ordered buffers is not safe as bmbt buffers may have been previously physically logged. The bmbt owner change algorithm needs to be updated to physically log buffers that are already dirty when/if they are encountered. This means that an extent swap will eventually require multiple rolling transactions to handle large btrees. In addition, all inode related changes must be logged before the bmbt owner change scan begins and can roll the transaction for the first time to preserve fs consistency via log recovery. In preparation for such fixes to the bmbt owner change algorithm, refactor the bmbt scan out of the extent fork swap code to the last operation before the transaction is committed. Update xfs_swap_extent_forks() to only set the inode log flags when an owner change scan is necessary. Update xfs_swap_extents() to trigger the owner change based on the inode log flags. Note that since the owner change now occurs after the extent fork swap, the inode btrees must be fixed up with the inode number of the current inode (similar to log recovery). Signed-off-by:
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Brian Foster authored
Extent swap uses xfs_btree_visit_blocks() to fix up bmbt block owners on v5 (!rmapbt) filesystems. The bmbt scan uses xfs_btree_lookup_get_block() to read bmbt blocks which verifies the current owner of the block against the parent inode of the bmbt. This works during extent swap because the bmbt owners are updated to the opposite inode number before the inode extent forks are swapped. The modified bmbt blocks are marked as ordered buffers which allows everything to commit in a single transaction. If the transaction commits to the log and the system crashes such that recovery of the extent swap is required, log recovery restarts the bmbt scan to fix up any bmbt blocks that may have not been written back before the crash. The log recovery bmbt scan occurs after the inode forks have been swapped, however. This causes the bmbt block owner verification to fail, leads to log recovery failure and requires xfs_repair to zap the log to recover. Define a new invalid inode owner flag to inform the btree block lookup mechanism that the current inode may be invalid with respect to the current owner of the bmbt block. Set this flag on the cursor used for change owner scans to allow this operation to work at runtime and during log recovery. Signed-off-by:
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Brian Foster authored
Ordered buffers are attached to transactions and pushed through the logging infrastructure just like normal buffers with the exception that they are not actually written to the log. Therefore, we don't need to log dirty ranges of ordered buffers. xfs_trans_log_buf() is called on ordered buffers to set up all of the dirty state on the transaction, buffer and log item and prepare the buffer for I/O. Now that xfs_trans_dirty_buf() is available, call it from xfs_trans_ordered_buf() so the latter is now mutually exclusive with xfs_trans_log_buf(). This reflects the implementation of ordered buffers and helps eliminate confusion over the need to log ranges of ordered buffers just to set up internal log state. Signed-off-by:
Allison Henderson <allison.henderson@oracle.com> Reviewed-by:
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Brian Foster authored
xfs_trans_log_buf() is responsible for logging the dirty segments of a buffer along with setting all of the necessary state on the transaction, buffer, bli, etc., to ensure that the associated items are marked as dirty and prepared for I/O. We have a couple use cases that need to to dirty a buffer in a transaction without actually logging dirty ranges of the buffer. One existing use case is ordered buffers, which are currently logged with arbitrary ranges to accomplish this even though the content of ordered buffers is never written to the log. Another pending use case is to relog an already dirty buffer across rolled transactions within the deferred operations infrastructure. This is required to prevent a held (XFS_BLI_HOLD) buffer from pinning the tail of the log. Refactor xfs_trans_log_buf() into a new function that contains all of the logic responsible to dirty the transaction, lidp, buffer and bli. This new function can be used in the future for the use cases outlined above. This patch does not introduce functional changes. Signed-off-by:
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Brian Foster authored
Ordered buffers pass through the logging infrastructure without ever being written to the log. The way this works is that the ordered buffer status is transferred to the log vector at commit time via the ->iop_size() callback. In xlog_cil_insert_format_items(), ordered log vectors bypass ->iop_format() processing altogether. Therefore it is unnecessary for xfs_buf_item_format() to handle ordered buffers. Remove the unnecessary logic and assert that an ordered buffer never reaches this point. Signed-off-by:
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Brian Foster authored
xfs_buf_item_unlock() historically checked the dirty state of the buffer by manually checking the buffer log formats for dirty segments. The introduction of ordered buffers invalidated this check because ordered buffers have dirty bli's but no dirty (logged) segments. The check was updated to accommodate ordered buffers by looking at the bli state first and considering the blf only if the bli is clean. This logic is safe but unnecessary. There is no valid case where the bli is clean yet the blf has dirty segments. The bli is set dirty whenever the blf is logged (via xfs_trans_log_buf()) and the blf is cleared in the only place BLI_DIRTY is cleared (xfs_trans_binval()). Remove the conditional blf dirty checks and replace with an assert that should catch any discrepencies between bli and blf dirty states. Refactor the old blf dirty check into a helper function to be used by the assert. Signed-off-by:
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Brian Foster authored
It checks a single flag and has one caller. It probably isn't worth its own function. Signed-off-by:
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Christoph Hellwig authored
And instead require callers to explicitly join the inode using xfs_defer_ijoin. Also consolidate the defer error handling in a few places using a goto label. Signed-off-by:
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Christoph Hellwig authored
Signed-off-by:
Dave Chinner <dchinner@redhat.com> Reviewed-by:
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Christoph Hellwig authored
Split xfs_trans_roll into a low-level helper that just rolls the actual transaction and a new higher level xfs_trans_roll_inode that takes care of logging and rejoining the inode. This gets rid of the NULL inode case, and allows to simplify the special cases in the deferred operation code. Signed-off-by:
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Omar Sandoval authored
After xfs_ifree_cluster() finds an inode in the radix tree and verifies that the inode number is what it expected, xfs_reclaim_inode() can swoop in and free it. xfs_ifree_cluster() will then happily continue working on the freed inode. Most importantly, it will mark the inode stale, which will probably be overwritten when the inode slab object is reallocated, but if it has already been reallocated then we can end up with an inode spuriously marked stale. In 8a17d7dd ("xfs: mark reclaimed inodes invalid earlier") we added a second check to xfs_iflush_cluster() to detect this race, but the similar RCU lookup in xfs_ifree_cluster() needs the same treatment. Signed-off-by:
Omar Sandoval <osandov@fb.com> Reviewed-by:
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Darrick J. Wong authored
When we introduced the bmap redo log items, we set MS_ACTIVE on the mountpoint and XFS_IRECOVERY on the inode to prevent unlinked inodes from being truncated prematurely during log recovery. This also had the effect of putting linked inodes on the lru instead of evicting them. Unfortunately, we neglected to find all those unreferenced lru inodes and evict them after finishing log recovery, which means that we leak them if anything goes wrong in the rest of xfs_mountfs, because the lru is only cleaned out on unmount. Therefore, evict unreferenced inodes in the lru list immediately after clearing MS_ACTIVE. Fixes: 17c12bcd ("xfs: when replaying bmap operations, don't let unlinked inodes get reaped") Signed-off-by:
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- 22 Aug, 2017 11 commits
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Carlos Maiolino authored
In a filesystem without finobt, the Space manager selects an AG to alloc a new inode, where xfs_dialloc_ag_inobt() will search the AG for the free slot chunk. When the new inode is in the same AG as its parent, the btree will be searched starting on the parent's record, and then retried from the top if no slot is available beyond the parent's record. To exit this loop though, xfs_dialloc_ag_inobt() relies on the fact that the btree must have a free slot available, once its callers relied on the agi->freecount when deciding how/where to allocate this new inode. In the case when the agi->freecount is corrupted, showing available inodes in an AG, when in fact there is none, this becomes an infinite loop. Add a way to stop the loop when a free slot is not found in the btree, making the function to fall into the whole AG scan which will then, be able to detect the corruption and shut the filesystem down. As pointed by Brian, this might impact performance, giving the fact we don't reset the search distance anymore when we reach the end of the tree, giving it fewer tries before falling back to the whole AG search, but it will only affect searches that start within 10 records to the end of the tree. Signed-off-by:
Carlos Maiolino <cmaiolino@redhat.com> Reviewed-by:
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Brian Foster authored
Torn write detection and tail overwrite detection can shift the log head and tail respectively in the event of CRC mismatch or corruption errors. Add a high-level log recovery tracepoint to dump the final log head/tail and make those values easily attainable in debug/diagnostic situations. Signed-off-by:
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Brian Foster authored
Torn write and tail overwrite detection both trigger only on -EFSBADCRC errors. While this is the most likely failure scenario for each condition, -EFSCORRUPTED is still possible in certain cases depending on what ends up on disk when a torn write or partial tail overwrite occurs. For example, an invalid log record h_len can lead to an -EFSCORRUPTED error when running the log recovery CRC pass. Therefore, update log head and tail verification to trigger the associated head/tail fixups in the event of -EFSCORRUPTED errors along with -EFSBADCRC. Also, -EFSCORRUPTED can currently be returned from xlog_do_recovery_pass() before rhead_blk is initialized if the first record encountered happens to be corrupted. This leads to an incorrect 'first_bad' return value. Initialize rhead_blk earlier in the function to address that problem as well. Signed-off-by:
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Brian Foster authored
Add an error injection tag to force log items in the AIL to the pinned state. This option can be used by test infrastructure to induce head behind tail conditions. Specifically, this is intended to be used by xfstests to reproduce log recovery problems after failed/corrupted log writes overwrite the last good tail LSN in the log. When enabled, AIL push attempts see log items in the AIL in the pinned state. This stalls metadata writeback and thus prevents the current tail of the log from moving forward. When disabled, subsequent AIL pushes observe the log items in their appropriate state and filesystem operation continues as normal. Signed-off-by:
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Brian Foster authored
If we consider the case where the tail (T) of the log is pinned long enough for the head (H) to push and block behind the tail, we can end up blocked in the following state without enough free space (f) in the log to satisfy a transaction reservation: 0 phys. log N [-------HffT---H'--T'---] The last good record in the log (before H) refers to T. The tail eventually pushes forward (T') leaving more free space in the log for writes to H. At this point, suppose space frees up in the log for the maximum of 8 in-core log buffers to start flushing out to the log. If this pushes the head from H to H', these next writes overwrite the previous tail T. This is safe because the items logged from T to T' have been written back and removed from the AIL. If the next log writes (H -> H') happen to fail and result in partial records in the log, the filesystem shuts down having overwritten T with invalid data. Log recovery correctly locates H on the subsequent mount, but H still refers to the now corrupted tail T. This results in log corruption errors and recovery failure. Since the tail overwrite results from otherwise correct runtime behavior, it is up to log recovery to try and deal with this situation. Update log recovery tail verification to run a CRC pass from the first record past the tail to the head. This facilitates error detection at T and moves the recovery tail to the first good record past H' (similar to truncating the head on torn write detection). If corruption is detected beyond the range possibly affected by the max number of iclogs, the log is legitimately corrupted and log recovery failure is expected. Signed-off-by:
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Brian Foster authored
Log tail verification currently only occurs when torn writes are detected at the head of the log. This was introduced because a change in the head block due to torn writes can lead to a change in the tail block (each log record header references the current tail) and the tail block should be verified before log recovery proceeds. Tail corruption is possible outside of torn write scenarios, however. For example, partial log writes can be detected and cleared during the initial head/tail block discovery process. If the partial write coincides with a tail overwrite, the log tail is corrupted and recovery fails. To facilitate correct handling of log tail overwites, update log recovery to always perform tail verification. This is necessary to detect potential tail overwrite conditions when torn writes may not have occurred. This changes normal (i.e., no torn writes) recovery behavior slightly to detect and return CRC related errors near the tail before actual recovery starts. Signed-off-by:
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Brian Foster authored
The high-level log recovery algorithm consists of two loops that walk the physical log and process log records from the tail to the head. The first loop handles the case where the tail is beyond the head and processes records up to the end of the physical log. The subsequent loop processes records from the beginning of the physical log to the head. Because log records can wrap around the end of the physical log, the first loop mentioned above must handle this case appropriately. Records are processed from in-core buffers, which means that this algorithm must split the reads of such records into two partial I/Os: 1.) from the beginning of the record to the end of the log and 2.) from the beginning of the log to the end of the record. This is further complicated by the fact that the log record header and log record data are read into independent buffers. The current handling of each buffer correctly splits the reads when either the header or data starts before the end of the log and wraps around the end. The data read does not correctly handle the case where the prior header read wrapped or ends on the physical log end boundary. blk_no is incremented to or beyond the log end after the header read to point to the record data, but the split data read logic triggers, attempts to read from an invalid log block and ultimately causes log recovery to fail. This can be reproduced fairly reliably via xfstests tests generic/047 and generic/388 with large iclog sizes (256k) and small (10M) logs. If the record header read has pushed beyond the end of the physical log, the subsequent data read is actually contiguous. Update the data read logic to detect the case where blk_no has wrapped, mod it against the log size to read from the correct address and issue one contiguous read for the log data buffer. The log record is processed as normal from the buffer(s), the loop exits after the current iteration and the subsequent loop picks up with the first new record after the start of the log. Signed-off-by:
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Carlos Maiolino authored
When a buffer has been failed during writeback, the inode items into it are kept flush locked, and are never resubmitted due the flush lock, so, if any buffer fails to be written, the items in AIL are never written to disk and never unlocked. This causes unmount operation to hang due these items flush locked in AIL, but this also causes the items in AIL to never be written back, even when the IO device comes back to normal. I've been testing this patch with a DM-thin device, creating a filesystem larger than the real device. When writing enough data to fill the DM-thin device, XFS receives ENOSPC errors from the device, and keep spinning on xfsaild (when 'retry forever' configuration is set). At this point, the filesystem can not be unmounted because of the flush locked items in AIL, but worse, the items in AIL are never retried at all (once xfs_inode_item_push() will skip the items that are flush locked), even if the underlying DM-thin device is expanded to the proper size. This patch fixes both cases, retrying any item that has been failed previously, using the infra-structure provided by the previous patch. Reviewed-by:
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Carlos Maiolino authored
With the current code, XFS never re-submit a failed buffer for IO, because the failed item in the buffer is kept in the flush locked state forever. To be able to resubmit an log item for IO, we need a way to mark an item as failed, if, for any reason the buffer which the item belonged to failed during writeback. Add a new log item callback to be used after an IO completion failure and make the needed clean ups. Reviewed-by:
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Eric Sandeen authored
When we do log recovery on a readonly mount, unlinked inode processing does not happen due to the readonly checks in xfs_inactive(), which are trying to prevent any I/O on a readonly mount. This is misguided - we do I/O on readonly mounts all the time, for consistency; for example, log recovery. So do the same RDONLY flag twiddling around xfs_log_mount_finish() as we do around xfs_log_mount(), for the same reason. This all cries out for a big rework but for now this is a simple fix to an obvious problem. Signed-off-by:
Eric Sandeen <sandeen@redhat.com> Reviewed-by:
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Eric Sandeen authored
There are dueling comments in the xfs code about intent for log writes when unmounting a readonly filesystem. In xfs_mountfs, we see the intent: /* * Now the log is fully replayed, we can transition to full read-only * mode for read-only mounts. This will sync all the metadata and clean * the log so that the recovery we just performed does not have to be * replayed again on the next mount. */ and it calls xfs_quiesce_attr(), but by the time we get to xfs_log_unmount_write(), it returns early for a RDONLY mount: * Don't write out unmount record on read-only mounts. Because of this, sequential ro mounts of a filesystem with a dirty log will replay the log each time, which seems odd. Fix this by writing an unmount record even for RO mounts, as long as norecovery wasn't specified (don't write a clean log record if a dirty log may still be there!) and the log device is writable. Signed-off-by:
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- 21 Aug, 2017 6 commits
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git://git.kernel.org/pub/scm/linux/kernel/git/davem/sparcLinus Torvalds authored
Pull sparc fixes from David Miller: "Just a couple small fixes, two of which have to do with gcc-7: 1) Don't clobber kernel fixed registers in __multi4 libgcc helper. 2) Fix a new uninitialized variable warning on sparc32 with gcc-7, from Thomas Petazzoni. 3) Adjust pmd_t initializer on sparc32 to make gcc happy. 4) If ATU isn't available, don't bark in the logs. From Tushar Dave" * git://git.kernel.org/pub/scm/linux/kernel/git/davem/sparc: sparc: kernel/pcic: silence gcc 7.x warning in pcibios_fixup_bus() sparc64: remove unnecessary log message sparc64: Don't clibber fixed registers in __multi4. mm: add pmd_t initializer __pmd() to work around a GCC bug. -
Thomas Petazzoni authored
When building the kernel for Sparc using gcc 7.x, the build fails with: arch/sparc/kernel/pcic.c: In function ‘pcibios_fixup_bus’: arch/sparc/kernel/pcic.c:647:8: error: ‘cmd’ may be used uninitialized in this function [-Werror=maybe-uninitialized] cmd |= PCI_COMMAND_IO; ^~ The simplified code looks like this: unsigned int cmd; [...] pcic_read_config(dev->bus, dev->devfn, PCI_COMMAND, 2, &cmd); [...] cmd |= PCI_COMMAND_IO; I.e, the code assumes that pcic_read_config() will always initialize cmd. But it's not the case. Looking at pcic_read_config(), if bus->number is != 0 or if the size is not one of 1, 2 or 4, *val will not be initialized. As a simple fix, we initialize cmd to zero at the beginning of pcibios_fixup_bus. Signed-off-by:Thomas Petazzoni <thomas.petazzoni@free-electrons.com> Signed-off-by:
David S. Miller <davem@davemloft.net>
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git://git.kernel.org/pub/scm/linux/kernel/git/vgupta/arcLinus Torvalds authored
Pull ARC fixes from Vineet Gupta: - PAE40 related updates - SLC errata for region ops - intc line masking by default * tag 'arc-4.13-rc7-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/vgupta/arc: arc: Mask individual IRQ lines during core INTC init ARCv2: PAE40: set MSB even if !CONFIG_ARC_HAS_PAE40 but PAE exists in SoC ARCv2: PAE40: Explicitly set MSB counterpart of SLC region ops addresses ARC: dma: implement dma_unmap_page and sg variant ARCv2: SLC: Make sure busy bit is set properly for region ops ARC: [plat-sim] Include this platform unconditionally ARC: [plat-axs10x]: prepare dts files for enabling PAE40 on axs103 ARC: defconfig: Cleanup from old Kconfig options
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git://git.kernel.org/pub/scm/linux/kernel/git/abelloni/linuxLinus Torvalds authored
Pull RTC fix from Alexandre Belloni: "Fix regmap configuration for ds1307" * tag 'rtc-4.13-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/abelloni/linux: rtc: ds1307: fix regmap config
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git://git.kernel.org/pub/scm/linux/kernel/git/davem/netLinus Torvalds authored
Pull networking fixes from David Miller: 1) Fix IGMP handling wrt VRF, from David Ahern. 2) Fix timer access to freed object in dccp, from Eric Dumazet. 3) Use kmalloc_array() in ptr_ring to avoid overflow cases which are triggerable by userspace. Also from Eric Dumazet. 4) Fix infinite loop in unmapping cleanup of nfp driver, from Colin Ian King. 5) Correct datagram peek handling of empty SKBs, from Matthew Dawson. 6) Fix use after free in TIPC, from Eric Dumazet. 7) When replacing a route in ipv6 we need to reset the round robin pointer, from Wei Wang. 8) Fix bug in pci_find_pcie_root_port() which was unearthed by the relaxed ordering changes, from Thierry Redding. I made sure to get an explicit ACK from Bjorn this time around :-) * git://git.kernel.org/pub/scm/linux/kernel/git/davem/net: (27 commits) ipv6: repair fib6 tree in failure case net_sched: fix order of queue length updates in qdisc_replace() tools lib bpf: improve warning switchdev: documentation: minor typo fixes bpf, doc: also add s390x as arch to sysctl description net: sched: fix NULL pointer dereference when action calls some targets rxrpc: Fix oops when discarding a preallocated service call irda: do not leak initialized list.dev to userspace net/mlx4_core: Enable 4K UAR if SRIOV module parameter is not enabled PCI: Allow PCI express root ports to find themselves tcp: when rearming RTO, if RTO time is in past then fire RTO ASAP net: check and errout if res->fi is NULL when RTM_F_FIB_MATCH is set ipv6: reset fn->rr_ptr when replacing route sctp: fully initialize the IPv6 address in sctp_v6_to_addr() tipc: fix use-after-free tun: handle register_netdevice() failures properly datagram: When peeking datagrams with offset < 0 don't skip empty skbs bpf, doc: improve sysctl knob description netxen: fix incorrect loop counter decrement nfp: fix infinite loop on umapping cleanup ... -
Oleg Nesterov authored
This was reported many times, and this was even mentioned in commit 52ee2dfd ("pids: refactor vnr/nr_ns helpers to make them safe") but somehow nobody bothered to fix the obvious problem: task_tgid_nr_ns() is not safe because task->group_leader points to nowhere after the exiting task passes exit_notify(), rcu_read_lock() can not help. We really need to change __unhash_process() to nullify group_leader, parent, and real_parent, but this needs some cleanups. Until then we can turn task_tgid_nr_ns() into another user of __task_pid_nr_ns() and fix the problem. Reported-by:
Troy Kensinger <tkensinger@google.com> Signed-off-by:
Oleg Nesterov <oleg@redhat.com> Signed-off-by:
Linus Torvalds <torvalds@linux-foundation.org>
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