Olaf said: Here's a short series of patches that produces a working
allmodconfig. Would be nice to see them go in so we can add build
coverage.
I've dropped patches 8 and 10 from the original set:
* [PATCH 08/10] (RISC-V: Set __ARCH_WANT_RENAMEAT to pick up generic
version) has a better fix that I've sent out for review, we don't want
renameat.
* [PATCH 10/10] (input: joystick: riscv has get_cycles) has already been
taken into Dmitry Torokhov's tree.
This merge contains the user-visible, ABI-breaking changes that we want
to make sure we have in Linux before our first release. Highlights
include:
* VDSO entries for clock_get/gettimeofday/getcpu have been added. These
are simple syscalls now, but we want to let glibc use them from the
start so we can make them faster later.
* A VDSO entry for instruction cache flushing has been added so
userspace can flush the instruction cache.
* The VDSO symbol versions for __vdso_cmpxchg{32,64} have been removed,
as those VDSO entries don't actually exist.
Conflicts:
arch/riscv/include/asm/tlbflush.h
This patch set is the result of some feedback that filtered through
after our original patch set was reviewed, some of which was the result
of me missing some email. It contains:
* A new READ_ONCE in arch_spin_is_locked()
* __test_and_op_bit_ord() is now actually ordered
* Improvements to various comments
* Removal of some dead code
Whoops -- I must have just been being an idiot again. Thanks to Segher
for finding the bug :).
CC: Segher Boessenkool <segher@kernel.crashing.org>
Signed-off-by: Palmer Dabbelt <palmer@sifive.com>
Introducing a new include/lib directory just for this file totally
messes up tab completion for include/linux, which is highly annoying.
Move it to include/linux where we have headers for all kinds of other
lib/ code as well.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Palmer Dabbelt <palmer@sifive.com>
We used to have some cmpxchg syscalls. They're no longer there, so we
no longer need the include.
CC: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Palmer Dabbelt <palmer@sifive.com>
Despite RISC-V having a direct 'fence.i' instruction available to
userspace (which we can't trap!), that's not actually viable when
running on Linux because the kernel might schedule a process on another
hart. There is no way for userspace to handle this without invoking the
kernel (as it doesn't know the thread->hart mappings), so we've defined
a RISC-V specific system call to flush the instruction cache.
This patch adds both a system call and a VDSO entry. If possible, we'd
like to avoid having the system call be considered part of the
user-facing ABI and instead restrict that to the VDSO entry -- both just
in general to avoid having additional user-visible ABI to maintain, and
because we'd prefer that users just call the VDSO entry because there
might be a better way to do this in the future (ie, one that doesn't
require entering the kernel).
Signed-off-by: Andrew Waterman <andrew@sifive.com>
Signed-off-by: Palmer Dabbelt <palmer@sifive.com>
The RISC-V ISA allows for instruction caches that are not coherent WRT
stores, even on a single hart. As a result, we need to explicitly flush
the instruction cache whenever marking a dirty page as executable in
order to preserve the correct system behavior.
Local instruction caches aren't that scary (our implementations actually
flush the cache, but RISC-V is defined to allow higher-performance
implementations to exist), but RISC-V defines no way to perform an
instruction cache shootdown. When explicitly asked to do so we can
shoot down remote instruction caches via an IPI, but this is a bit on
the slow side.
Instead of requiring an IPI to all harts whenever marking a page as
executable, we simply flush the currently running harts. In order to
maintain correct behavior, we additionally mark every other hart as
needing a deferred instruction cache which will be taken before anything
runs on it.
Signed-off-by: Andrew Waterman <andrew@sifive.com>
Signed-off-by: Palmer Dabbelt <palmer@sifive.com>
Fixes:
include/asm-generic/mm_hooks.h:20:11: warning: 'struct vm_area_struct' declared inside parameter list will not be visible outside of this definition or declaration
include/asm-generic/mm_hooks.h:19:38: warning: 'struct mm_struct' declared inside parameter list will not be visible outside of this definition or declaration
Signed-off-by: Olof Johansson <olof@lixom.net>
Signed-off-by: Palmer Dabbelt <palmer@sifive.com>
Fixes the following on allmodconfig build:
profile.c:(.text+0x3e4): undefined reference to `setup_profiling_timer'
Signed-off-by: Olof Johansson <olof@lixom.net>
Signed-off-by: Palmer Dabbelt <palmer@sifive.com>
These are the ones needed by current allmodconfig, so add them instead
of everything other architectures are exporting -- the rest can be
added on demand later if needed.
Signed-off-by: Olof Johansson <olof@lixom.net>
Signed-off-by: Palmer Dabbelt <palmer@sifive.com>
Needed by some modules (exported by other architectures).
Signed-off-by: Olof Johansson <olof@lixom.net>
Signed-off-by: Palmer Dabbelt <palmer@sifive.com>
include <linux/types.h> for __iomem definition. Also, add volatile to
iounmap() like other architectures have it to avoid "discarding
volatile" warnings from some drivers.
Finally, explicitly promote the base address for INB/OUTB functions to
avoid some old legacy drivers complaining about int-to-ptr promotions.
The drivers are unlikely to work but they're included in allmodconfig
so the warnings are noisy.
Fixes, among other warnings, these with allmodconfig:
../arch/riscv/include/asm/io.h:24:21: error: expected '=', ',', ';', 'asm' or '__attribute__' before '*' token
extern void __iomem *ioremap(phys_addr_t offset, unsigned long size);
sound/pci/echoaudio/echoaudio.c: In function 'snd_echo_free':
sound/pci/echoaudio/echoaudio.c:1879:10: warning: passing argument 1 of 'iounmap' discards 'volatile' qualifier from pointer target type [-Wdiscarded-qualifiers]
Signed-off-by: Olof Johansson <olof@lixom.net>
Signed-off-by: Palmer Dabbelt <palmer@sifive.com>
INT and SHORT are used by some drivers that pull in the include files,
so prefixing helps avoid namespace conflicts. Other constructs in the
same file already uses this.
Fixes, among others, these warnings with allmodconfig:
../sound/core/pcm_misc.c:43:0: warning: "INT" redefined
#define INT __force int
Signed-off-by: Olof Johansson <olof@lixom.net>
Signed-off-by: Palmer Dabbelt <palmer@sifive.com>
Fixes this from allmodconfig:
drivers/tty/serial/earlycon.c:27:10: fatal error: asm/serial.h: No such file or directory
Signed-off-by: Olof Johansson <olof@lixom.net>
Signed-off-by: Palmer Dabbelt <palmer@sifive.com>
This was removed from the other architectures in commit
952111d7db ("arch: Remove spin_unlock_wait() arch-specific
definitions"). That landed between when we got upstream and when our
patches were reviewed, so this is a followup patch.
Signed-off-by: Palmer Dabbelt <palmer@sifive.com>
This is just a comment change, but it's one that bit me on the mailing
list. It turns out that issuing a `sfence.vma` enforces instruction
cache ordering in addition to TLB ordering. This isn't explicitly
called out in the ISA manual, but Andrew will be making that more clear
in a future revision.
CC: Andrew Waterman <andrew@sifive.com>
Signed-off-by: Palmer Dabbelt <palmer@sifive.com>
I mis-read the documentation. After looking at it again the
documentation is actually as clear as it can be, it's just that I didn't
actually read it in order and therefor did the wrong thing.
Signed-off-by: Palmer Dabbelt <palmer@sifive.com>
Our atomics are generated from a complicated series of preprocessor
macros, each of which is slightly different from the last. When writing
the macros I'd accidentally left some unused arguments floating around.
This patch removes the unused macro arguments.
Signed-off-by: Palmer Dabbelt <palmer@dabbelt.com>
For now these are just placeholders that execute the syscall. We will
later optimize them to avoid kernel crossings, but we'd like to have the
VDSO entries from the first released kernel version to make the ABI
simpler.
Signed-off-by: Andrew Waterman <andrew@sifive.com>
Signed-off-by: Palmer Dabbelt <palmer@sifive.com>
Pull ARM fixes from Russell King:
- LPAE fixes for kernel-readonly regions
- Fix for get_user_pages_fast on LPAE systems
- avoid tying decompressor to a particular platform if DEBUG_LL is
enabled
- BUG if we attempt to return to userspace but the to-be-restored PSR
value keeps us in privileged mode (defeating an issue that ftracetest
found)
* 'fixes' of git://git.armlinux.org.uk/~rmk/linux-arm:
ARM: BUG if jumping to usermode address in kernel mode
ARM: 8722/1: mm: make STRICT_KERNEL_RWX effective for LPAE
ARM: 8721/1: mm: dump: check hardware RO bit for LPAE
ARM: make decompressor debug output user selectable
ARM: fix get_user_pages_fast
Pull irq fixes from Thomas Glexiner:
- unbreak the irq trigger type check for legacy platforms
- a handful fixes for ARM GIC v3/4 interrupt controllers
- a few trivial fixes all over the place
* 'irq-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
genirq/matrix: Make - vs ?: Precedence explicit
irqchip/imgpdc: Use resource_size function on resource object
irqchip/qcom: Fix u32 comparison with value less than zero
irqchip/exiu: Fix return value check in exiu_init()
irqchip/gic-v3-its: Remove artificial dependency on PCI
irqchip/gic-v4: Add forward definition of struct irq_domain_ops
irqchip/gic-v3: pr_err() strings should end with newlines
irqchip/s3c24xx: pr_err() strings should end with newlines
irqchip/gic-v3: Fix ppi-partitions lookup
irqchip/gic-v4: Clear IRQ_DISABLE_UNLAZY again if mapping fails
genirq: Track whether the trigger type has been set
Pull misc x86 fixes from Ingo Molnar:
- topology enumeration fixes
- KASAN fix
- two entry fixes (not yet the big series related to KASLR)
- remove obsolete code
- instruction decoder fix
- better /dev/mem sanity checks, hopefully working better this time
- pkeys fixes
- two ACPI fixes
- 5-level paging related fixes
- UMIP fixes that should make application visible faults more debuggable
- boot fix for weird virtualization environment
* 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (24 commits)
x86/decoder: Add new TEST instruction pattern
x86/PCI: Remove unused HyperTransport interrupt support
x86/umip: Fix insn_get_code_seg_params()'s return value
x86/boot/KASLR: Remove unused variable
x86/entry/64: Add missing irqflags tracing to native_load_gs_index()
x86/mm/kasan: Don't use vmemmap_populate() to initialize shadow
x86/entry/64: Fix entry_SYSCALL_64_after_hwframe() IRQ tracing
x86/pkeys/selftests: Fix protection keys write() warning
x86/pkeys/selftests: Rename 'si_pkey' to 'siginfo_pkey'
x86/mpx/selftests: Fix up weird arrays
x86/pkeys: Update documentation about availability
x86/umip: Print a warning into the syslog if UMIP-protected instructions are used
x86/smpboot: Fix __max_logical_packages estimate
x86/topology: Avoid wasting 128k for package id array
perf/x86/intel/uncore: Cache logical pkg id in uncore driver
x86/acpi: Reduce code duplication in mp_override_legacy_irq()
x86/acpi: Handle SCI interrupts above legacy space gracefully
x86/boot: Fix boot failure when SMP MP-table is based at 0
x86/mm: Limit mmap() of /dev/mem to valid physical addresses
x86/selftests: Add test for mapping placement for 5-level paging
...
Pull scheduler fixes from Ingo Molnar:
"Misc fixes: a documentation fix, a Sparse warning fix and a debugging
fix"
* 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
sched/debug: Fix task state recording/printout
sched/deadline: Don't use dubious signed bitfields
sched/deadline: Fix the description of runtime accounting in the documentation
Pull perf fixes from Ingo Molnar:
"Misc fixes: two PMU driver fixes and a memory leak fix"
* 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
perf/core: Fix memory leak triggered by perf --namespace
perf/x86/intel/uncore: Add event constraint for BDX PCU
perf/x86/intel: Hide TSX events when RTM is not supported
Pull static key fix from Ingo Molnar:
"Fix a boot warning related to bad init ordering of the static keys
self-test"
* 'locking-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
jump_label: Invoke jump_label_test() via early_initcall()
Pull objtool fixes from Ingo Molnar:
"A handful of objtool fixes, most of them related to making the UAPI
header-syncing warnings easier to read and easier to act upon"
* 'core-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
tools/headers: Sync objtool UAPI header
objtool: Fix cross-build
objtool: Move kernel headers/code sync check to a script
objtool: Move synced files to their original relative locations
objtool: Make unreachable annotation inline asms explicitly volatile
objtool: Add a comment for the unreachable annotation macros
Detect if we are returning to usermode via the normal kernel exit paths
but the saved PSR value indicates that we are in kernel mode. This
could occur due to corrupted stack state, which has been observed with
"ftracetest".
This ensures that we catch the problem case before we get to user code.
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
Pull timer updates from Thomas Gleixner:
- The final conversion of timer wheel timers to timer_setup().
A few manual conversions and a large coccinelle assisted sweep and
the removal of the old initialization mechanisms and the related
code.
- Remove the now unused VSYSCALL update code
- Fix permissions of /proc/timer_list. I still need to get rid of that
file completely
- Rename a misnomed clocksource function and remove a stale declaration
* 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (27 commits)
m68k/macboing: Fix missed timer callback assignment
treewide: Remove TIMER_FUNC_TYPE and TIMER_DATA_TYPE casts
timer: Remove redundant __setup_timer*() macros
timer: Pass function down to initialization routines
timer: Remove unused data arguments from macros
timer: Switch callback prototype to take struct timer_list * argument
timer: Pass timer_list pointer to callbacks unconditionally
Coccinelle: Remove setup_timer.cocci
timer: Remove setup_*timer() interface
timer: Remove init_timer() interface
treewide: setup_timer() -> timer_setup() (2 field)
treewide: setup_timer() -> timer_setup()
treewide: init_timer() -> setup_timer()
treewide: Switch DEFINE_TIMER callbacks to struct timer_list *
s390: cmm: Convert timers to use timer_setup()
lightnvm: Convert timers to use timer_setup()
drivers/net: cris: Convert timers to use timer_setup()
drm/vc4: Convert timers to use timer_setup()
block/laptop_mode: Convert timers to use timer_setup()
net/atm/mpc: Avoid open-coded assignment of timer callback function
...
Pull ARC updates from Vineet Gupta:
- more changes for HS48 cores: supporting MMUv5, detecting new
micro-arch gizmos
- axs10x platform wiring up reset driver merged in this cycle
- ARC perf driver optimizations
* tag 'arc-4.15-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/vgupta/arc:
ARC: perf: avoid vmalloc backed mmap
ARCv2: perf: optimize given that num counters <= 32
ARCv2: perf: tweak overflow interrupt
ARC: [plat-axs10x] DTS: Add reset controller node to manage ethernet reset
ARCv2: boot log: updates for HS48: dual-issue, ECC, Loop Buffer
ARCv2: Accomodate HS48 MMUv5 by relaxing MMU ver checking
ARC: [plat-axs10x] auto-select AXS101 or AXS103 given the ISA config
Pull more Kbuild updates from Masahiro Yamada:
- use 'pwd' instead of '/bin/pwd' for portability
- clean up Makefiles
- fix ld-option for clang
- fix malloc'ed data size in Kconfig
- fix parallel building along with coccicheck
- fix a minor issue of package building
- prompt to use "rpm-pkg" instead of "rpm"
- clean up *.i and *.lst patterns by "make clean"
* tag 'kbuild-v4.15-2' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild:
kbuild: drop $(extra-y) from real-objs-y
kbuild: clean up *.i and *.lst patterns by make clean
kbuild: rpm: prompt to use "rpm-pkg" if "rpm" target is used
kbuild: pkg: use --transform option to prefix paths in tar
coccinelle: fix parallel build with CHECK=scripts/coccicheck
kconfig/symbol.c: use correct pointer type argument for sizeof
kbuild: Set KBUILD_CFLAGS before incl. arch Makefile
kbuild: remove all dummy assignments to obj-
kbuild: create built-in.o automatically if parent directory wants it
kbuild: /bin/pwd -> pwd
Pull AFS fixes from David Howells:
- Make AFS file locking work again.
- Don't write to a page that's being written out, but wait for it to
complete.
- Do d_drop() and d_add() in the right places.
- Put keys on error paths.
- Remove some redundant code.
* tag 'afs-fixes-20171124' of git://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs:
afs: remove redundant assignment of dvnode to itself
afs: cell: Remove unnecessary code in afs_lookup_cell
afs: Fix signal handling in some file ops
afs: Fix some dentry handling in dir ops and missing key_puts
afs: Make afs_write_begin() avoid writing to a page that's being stored
afs: Fix file locking
Pull KVM updates from Radim Krčmář:
"Trimmed second batch of KVM changes for Linux 4.15:
- GICv4 Support for KVM/ARM
- re-introduce support for CPUs without virtual NMI (cc stable) and
allow testing of KVM without virtual NMI on available CPUs
- fix long-standing performance issues with assigned devices on AMD
(cc stable)"
* tag 'kvm-4.15-2' of git://git.kernel.org/pub/scm/virt/kvm/kvm: (30 commits)
kvm: vmx: Allow disabling virtual NMI support
kvm: vmx: Reinstate support for CPUs without virtual NMI
KVM: SVM: obey guest PAT
KVM: arm/arm64: Don't queue VLPIs on INV/INVALL
KVM: arm/arm64: Fix GICv4 ITS initialization issues
KVM: arm/arm64: GICv4: Theory of operations
KVM: arm/arm64: GICv4: Enable VLPI support
KVM: arm/arm64: GICv4: Prevent userspace from changing doorbell affinity
KVM: arm/arm64: GICv4: Prevent a VM using GICv4 from being saved
KVM: arm/arm64: GICv4: Enable virtual cpuif if VLPIs can be delivered
KVM: arm/arm64: GICv4: Hook vPE scheduling into vgic flush/sync
KVM: arm/arm64: GICv4: Use the doorbell interrupt as an unblocking source
KVM: arm/arm64: GICv4: Add doorbell interrupt handling
KVM: arm/arm64: GICv4: Use pending_last as a scheduling hint
KVM: arm/arm64: GICv4: Handle INVALL applied to a vPE
KVM: arm/arm64: GICv4: Propagate property updates to VLPIs
KVM: arm/arm64: GICv4: Handle MOVALL applied to a vPE
KVM: arm/arm64: GICv4: Handle CLEAR applied to a VLPI
KVM: arm/arm64: GICv4: Propagate affinity changes to the physical ITS
KVM: arm/arm64: GICv4: Unmap VLPI when freeing an LPI
...
Pull powerpc fixes from Michael Ellerman:
"A small batch of fixes, about 50% tagged for stable and the rest for
recently merged code.
There's one more fix for the >128T handling on hash. Once a process
had requested a single mmap above 128T we would then always search
above 128T. The correct behaviour is to consider the hint address in
isolation for each mmap request.
Then a couple of fixes for the IMC PMU, a missing EXPORT_SYMBOL in
VAS, a fix for STRICT_KERNEL_RWX on 32-bit, and a fix to correctly
identify P9 DD2.1 but in code that is currently not used by default.
Thanks to: Aneesh Kumar K.V, Christophe Leroy, Madhavan Srinivasan,
Sukadev Bhattiprolu"
* tag 'powerpc-4.15-2' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux:
powerpc/64s: Fix Power9 DD2.1 logic in DT CPU features
powerpc/perf: Fix IMC_MAX_PMU macro
powerpc/perf: Fix pmu_count to count only nest imc pmus
powerpc: Fix boot on BOOK3S_32 with CONFIG_STRICT_KERNEL_RWX
powerpc/perf/imc: Use cpu_to_node() not topology_physical_package_id()
powerpc/vas: Export chip_to_vas_id()
powerpc/64s/slice: Use addr limit when computing slice mask
Pull SCSI target updates from Nicholas Bellinger:
"This series is predominantly bug-fixes, with a few small improvements
that have been outstanding over the last release cycle.
As usual, the associated bug-fixes have CC' tags for stable.
Also, things have been particularly quiet wrt new developments the
last months, with most folks continuing to focus on stability atop 4.x
stable kernels for their respective production configurations.
Also at this point, the stable trees have been synced up with
mainline. This will continue to be a priority, as production users
tend to run exclusively atop stable kernels, a few releases behind
mainline.
The highlights include:
- Fix PR PREEMPT_AND_ABORT null pointer dereference regression in
v4.11+ (tangwenji)
- Fix OOPs during removing TCMU device (Xiubo Li + Zhang Zhuoyu)
- Add netlink command reply supported option for each device (Kenjiro
Nakayama)
- cxgbit: Abort the TCP connection in case of data out timeout (Varun
Prakash)
- Fix PR/ALUA file path truncation (David Disseldorp)
- Fix double se_cmd completion during ->cmd_time_out (Mike Christie)
- Fix QUEUE_FULL + SCSI task attribute handling in 4.1+ (Bryant Ly +
nab)
- Fix quiese during transport_write_pending_qf endless loop (nab)
- Avoid early CMD_T_PRE_EXECUTE failures during ABORT_TASK in 3.14+
(Don White + nab)"
* 'for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/nab/target-pending: (35 commits)
tcmu: Add a missing unlock on an error path
tcmu: Fix some memory corruption
iscsi-target: Fix non-immediate TMR reference leak
iscsi-target: Make TASK_REASSIGN use proper se_cmd->cmd_kref
target: Avoid early CMD_T_PRE_EXECUTE failures during ABORT_TASK
target: Fix quiese during transport_write_pending_qf endless loop
target: Fix caw_sem leak in transport_generic_request_failure
target: Fix QUEUE_FULL + SCSI task attribute handling
iSCSI-target: Use common error handling code in iscsi_decode_text_input()
target/iscsi: Detect conn_cmd_list corruption early
target/iscsi: Fix a race condition in iscsit_add_reject_from_cmd()
target/iscsi: Modify iscsit_do_crypto_hash_buf() prototype
target/iscsi: Fix endianness in an error message
target/iscsi: Use min() in iscsit_dump_data_payload() instead of open-coding it
target/iscsi: Define OFFLOAD_BUF_SIZE once
target: Inline transport_put_cmd()
target: Suppress gcc 7 fallthrough warnings
target: Move a declaration of a global variable into a header file
tcmu: fix double se_cmd completion
target: return SAM_STAT_TASK_SET_FULL for TCM_OUT_OF_RESOURCES
...
The assignment of dvnode to itself is redundant and can be removed.
Cleans up warning detected by cppcheck:
fs/afs/dir.c:975: (warning) Redundant assignment of 'dvnode' to itself.
Fixes: d2ddc776a4 ("afs: Overhaul volume and server record caching and fileserver rotation")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: David Howells <dhowells@redhat.com>
afs_mkdir(), afs_create(), afs_link() and afs_symlink() all need to drop
the target dentry if a signal causes the operation to be killed immediately
before we try to contact the server.
Signed-off-by: David Howells <dhowells@redhat.com>
Fix some of dentry handling in AFS directory ops:
(1) Do d_drop() on the new_dentry before assigning a new inode to it in
afs_vnode_new_inode(). It's fine to do this before calling afs_iget()
because the operation has taken place on the server.
(2) Replace d_instantiate()/d_rehash() with d_add().
(3) Don't d_drop() the new_dentry in afs_rename() on error.
Also fix afs_link() and afs_rename() to call key_put() on all error paths
where the key is taken.
Signed-off-by: David Howells <dhowells@redhat.com>
Make afs_write_begin() wait for a page that's marked PG_writeback because:
(1) We need to avoid interference with the data being stored so that the
data on the server ends up in a defined state.
(2) page->private is used to track the window of dirty data within a page,
but it's also used by the storage code to track what's being written,
being cleared by the completion notification. Ownership can't be
relinquished by the storage code until completion because it a store
fails, the data must be remarked dirty.
Tracing shows something like the following (edited):
x86_64-linux-gn-15940 [1] afs_page_dirty: vn=ffff8800bef33800 9c75 begin 0-125
kworker/u8:3-114 [2] afs_page_dirty: vn=ffff8800bef33800 9c75 store+ 0-125
x86_64-linux-gn-15940 [1] afs_page_dirty: vn=ffff8800bef33800 9c75 begin 0-2052
kworker/u8:3-114 [2] afs_page_dirty: vn=ffff8800bef33800 9c75 clear 0-2052
kworker/u8:3-114 [2] afs_page_dirty: vn=ffff8800bef33800 9c75 store 0-0
kworker/u8:3-114 [2] afs_page_dirty: vn=ffff8800bef33800 9c75 WARN 0-0
The clear (completion) corresponding to the store+ (store continuation from
a previous page) happens between the second begin (afs_write_begin) and the
store corresponding to that. This results in the second store not seeing
any data to write back, leading to the following warning:
WARNING: CPU: 2 PID: 114 at ../fs/afs/write.c:403 afs_write_back_from_locked_page+0x19d/0x76c [kafs]
Modules linked in: kafs(E)
CPU: 2 PID: 114 Comm: kworker/u8:3 Tainted: G E 4.14.0-fscache+ #242
Hardware name: ASUS All Series/H97-PLUS, BIOS 2306 10/09/2014
Workqueue: writeback wb_workfn (flush-afs-2)
task: ffff8800cad72600 task.stack: ffff8800cad44000
RIP: 0010:afs_write_back_from_locked_page+0x19d/0x76c [kafs]
RSP: 0018:ffff8800cad47aa0 EFLAGS: 00010246
RAX: 0000000000000001 RBX: ffff8800bef33a20 RCX: 0000000000000000
RDX: 000000000000000f RSI: ffffffff81c5d0e0 RDI: ffff8800cad72e78
RBP: ffff8800d31ea1e8 R08: ffff8800c1358000 R09: ffff8800ca00e400
R10: ffff8800cad47a38 R11: ffff8800c5d9e400 R12: 0000000000000000
R13: ffffea0002d9df00 R14: ffffffffa0023c1c R15: 0000000000007fdf
FS: 0000000000000000(0000) GS:ffff8800ca700000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f85ac6c4000 CR3: 0000000001c10001 CR4: 00000000001606e0
Call Trace:
? clear_page_dirty_for_io+0x23a/0x267
afs_writepages_region+0x1be/0x286 [kafs]
afs_writepages+0x60/0x127 [kafs]
do_writepages+0x36/0x70
__writeback_single_inode+0x12f/0x635
writeback_sb_inodes+0x2cc/0x452
__writeback_inodes_wb+0x68/0x9f
wb_writeback+0x208/0x470
? wb_workfn+0x22b/0x565
wb_workfn+0x22b/0x565
? worker_thread+0x230/0x2ac
process_one_work+0x2cc/0x517
? worker_thread+0x230/0x2ac
worker_thread+0x1d4/0x2ac
? rescuer_thread+0x29b/0x29b
kthread+0x15d/0x165
? kthread_create_on_node+0x3f/0x3f
? call_usermodehelper_exec_async+0x118/0x11f
ret_from_fork+0x24/0x30
Signed-off-by: David Howells <dhowells@redhat.com>
