Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
See Documentation/00-INDEX for a list of what is contained in each file.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.
code
Clone this repository
https://tangled.org/tjh.dev/kernel
git@gordian.tjh.dev:tjh.dev/kernel
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Pull vfs fixes from Al Viro.
- fix io_destroy()/aio_complete() race
- the vfs_open() change to get rid of open_check_o_direct() boilerplate
was nice, but buggy. Al has a patch avoiding a revert, but that's
definitely not a last-day fodder, so for now revert it is...
* 'fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
Revert "fs: fold open_check_o_direct into do_dentry_open"
fix io_destroy()/aio_complete() race
Pull scheduler fixes from Thomas Gleixner:
- two patches addressing the problem that the scheduler allows under
certain conditions user space tasks to be scheduled on CPUs which are
not yet fully booted which causes a few subtle and hard to debug
issue
- add a missing runqueue clock update in the deadline scheduler which
triggers a warning under certain circumstances
- fix a silly typo in the scheduler header file
* 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
sched/headers: Fix typo
sched/deadline: Fix missing clock update
sched/core: Require cpu_active() in select_task_rq(), for user tasks
sched/core: Fix rules for running on online && !active CPUs
This reverts commit cab64df194667dc5d9d786f0a895f647f5501c0d.
Having vfs_open() in some cases drop the reference to
struct file combined with
error = vfs_open(path, f, cred);
if (error) {
put_filp(f);
return ERR_PTR(error);
}
return f;
is flat-out wrong. It used to be
error = vfs_open(path, f, cred);
if (!error) {
/* from now on we need fput() to dispose of f */
error = open_check_o_direct(f);
if (error) {
fput(f);
f = ERR_PTR(error);
}
} else {
put_filp(f);
f = ERR_PTR(error);
}
and sure, having that open_check_o_direct() boilerplate gotten rid of is
nice, but not that way...
Worse, another call chain (via finish_open()) is FUBAR now wrt
FILE_OPENED handling - in that case we get error returned, with file
already hit by fput() *AND* FILE_OPENED not set. Guess what happens in
path_openat(), when it hits
if (!(opened & FILE_OPENED)) {
BUG_ON(!error);
put_filp(file);
}
The root cause of all that crap is that the callers of do_dentry_open()
have no way to tell which way did it fail; while that could be fixed up
(by passing something like int *opened to do_dentry_open() and have it
marked if we'd called ->open()), it's probably much too late in the
cycle to do so right now.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Pull perf tooling fixes from Thomas Gleixner:
- fix 'perf test Session topology' segfault on s390 (Thomas Richter)
- fix NULL return handling in bpf__prepare_load() (YueHaibing)
- fix indexing on Coresight ETM packet queue decoder (Mathieu Poirier)
- fix perf.data format description of NRCPUS header (Arnaldo Carvalho
de Melo)
- update perf.data documentation section on cpu topology
- handle uncore event aliases in small groups properly (Kan Liang)
- add missing perf_sample.addr into python sample dictionary (Leo Yan)
* 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
perf tools: Fix perf.data format description of NRCPUS header
perf script python: Add addr into perf sample dict
perf data: Update documentation section on cpu topology
perf cs-etm: Fix indexing for decoder packet queue
perf bpf: Fix NULL return handling in bpf__prepare_load()
perf test: "Session topology" dumps core on s390
perf parse-events: Handle uncore event aliases in small groups properly
I cannot spell 'throttling'.
Signed-off-by: Davidlohr Bueso <dbueso@suse.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20180530224940.17839-1-dave@stgolabs.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
If io_destroy() gets to cancelling everything that can be cancelled and
gets to kiocb_cancel() calling the function driver has left in ->ki_cancel,
it becomes vulnerable to a race with IO completion. At that point req
is already taken off the list and aio_complete() does *NOT* spin until
we (in free_ioctx_users()) releases ->ctx_lock. As the result, it proceeds
to kiocb_free(), freing req just it gets passed to ->ki_cancel().
Fix is simple - remove from the list after the call of kiocb_cancel(). All
instances of ->ki_cancel() already have to cope with the being called with
iocb still on list - that's what happens in io_cancel(2).
Cc: stable@kernel.org
Fixes: 0460fef2a921 "aio: use cancellation list lazily"
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Pull networking fixes from David Miller:
1) Infinite loop in _decode_session6(), from Eric Dumazet.
2) Pass correct argument to nla_strlcpy() in netfilter, also from Eric
Dumazet.
3) Out of bounds memory access in ipv6 srh code, from Mathieu Xhonneux.
4) NULL deref in XDP_REDIRECT handling of tun driver, from Toshiaki
Makita.
5) Incorrect idr release in cls_flower, from Paul Blakey.
6) Probe error handling fix in davinci_emac, from Dan Carpenter.
7) Memory leak in XPS configuration, from Alexander Duyck.
8) Use after free with cloned sockets in kcm, from Kirill Tkhai.
9) MTU handling fixes fo ip_tunnel and ip6_tunnel, from Nicolas
Dichtel.
10) Fix UAPI hole in bpf data structure for 32-bit compat applications,
from Daniel Borkmann.
* git://git.kernel.org/pub/scm/linux/kernel/git/davem/net: (33 commits)
bpf: fix uapi hole for 32 bit compat applications
net: usb: cdc_mbim: add flag FLAG_SEND_ZLP
ip6_tunnel: remove magic mtu value 0xFFF8
ip_tunnel: restore binding to ifaces with a large mtu
net: dsa: b53: Add BCM5389 support
kcm: Fix use-after-free caused by clonned sockets
net-sysfs: Fix memory leak in XPS configuration
ixgbe: fix parsing of TC actions for HW offload
net: ethernet: davinci_emac: fix error handling in probe()
net/ncsi: Fix array size in dumpit handler
cls_flower: Fix incorrect idr release when failing to modify rule
net/sonic: Use dma_mapping_error()
xfrm Fix potential error pointer dereference in xfrm_bundle_create.
vhost_net: flush batched heads before trying to busy polling
tun: Fix NULL pointer dereference in XDP redirect
be2net: Fix error detection logic for BE3
net: qmi_wwan: Add Netgear Aircard 779S
mlxsw: spectrum: Forbid creation of VLAN 1 over port/LAG
atm: zatm: fix memcmp casting
iwlwifi: pcie: compare with number of IRQs requested for, not number of CPUs
...
Pull perf/urgent fixes from Arnaldo Carvalho de Melo:
- Fix 'perf test Session topology' segfault on s390 (Thomas Richter)
- Fix NULL return handling in bpf__prepare_load() (YueHaibing)
- Fix indexing on Coresight ETM packet queue decoder (Mathieu Poirier)
- Fix perf.data format description of NRCPUS header (Arnaldo Carvalho de Melo)
- Update perf.data documentation section on cpu topology
- Handle uncore event aliases in small groups properly (Kan Liang)
- Add missing perf_sample.addr into python sample dictionary (Leo Yan)
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
A missing clock update is causing the following warning:
rq->clock_update_flags < RQCF_ACT_SKIP
WARNING: CPU: 10 PID: 0 at kernel/sched/sched.h:963 inactive_task_timer+0x5d6/0x720
Call Trace:
<IRQ>
__hrtimer_run_queues+0x10f/0x530
hrtimer_interrupt+0xe5/0x240
smp_apic_timer_interrupt+0x79/0x2b0
apic_timer_interrupt+0xf/0x20
</IRQ>
do_idle+0x203/0x280
cpu_startup_entry+0x6f/0x80
start_secondary+0x1b0/0x200
secondary_startup_64+0xa5/0xb0
hardirqs last enabled at (793919): [<ffffffffa27c5f6e>] cpuidle_enter_state+0x9e/0x360
hardirqs last disabled at (793920): [<ffffffffa2a0096e>] interrupt_entry+0xce/0xe0
softirqs last enabled at (793922): [<ffffffffa20bef78>] irq_enter+0x68/0x70
softirqs last disabled at (793921): [<ffffffffa20bef5d>] irq_enter+0x4d/0x70
This happens because inactive_task_timer() calls sub_running_bw() (if
TASK_DEAD and non_contending) that might trigger a schedutil update,
which might access the clock. Clock is however currently updated only
later in inactive_task_timer() function.
Fix the problem by updating the clock right after task_rq_lock().
Reported-by: kernel test robot <xiaolong.ye@intel.com>
Signed-off-by: Juri Lelli <juri.lelli@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Claudio Scordino <claudio@evidence.eu.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Luca Abeni <luca.abeni@santannapisa.it>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20180530160809.9074-1-juri.lelli@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
kill_ioctx() used to have an explicit RCU delay between removing the
reference from ->ioctx_table and percpu_ref_kill() dropping the refcount.
At some point that delay had been removed, on the theory that
percpu_ref_kill() itself contained an RCU delay. Unfortunately, that was
the wrong kind of RCU delay and it didn't care about rcu_read_lock() used
by lookup_ioctx(). As the result, we could get ctx freed right under
lookup_ioctx(). Tejun has fixed that in a6d7cff472e ("fs/aio: Add explicit
RCU grace period when freeing kioctx"); however, that fix is not enough.
Suppose io_destroy() from one thread races with e.g. io_setup() from another;
CPU1 removes the reference from current->mm->ioctx_table[...] just as CPU2
has picked it (under rcu_read_lock()). Then CPU1 proceeds to drop the
refcount, getting it to 0 and triggering a call of free_ioctx_users(),
which proceeds to drop the secondary refcount and once that reaches zero
calls free_ioctx_reqs(). That does
INIT_RCU_WORK(&ctx->free_rwork, free_ioctx);
queue_rcu_work(system_wq, &ctx->free_rwork);
and schedules freeing the whole thing after RCU delay.
In the meanwhile CPU2 has gotten around to percpu_ref_get(), bumping the
refcount from 0 to 1 and returned the reference to io_setup().
Tejun's fix (that queue_rcu_work() in there) guarantees that ctx won't get
freed until after percpu_ref_get(). Sure, we'd increment the counter before
ctx can be freed. Now we are out of rcu_read_lock() and there's nothing to
stop freeing of the whole thing. Unfortunately, CPU2 assumes that since it
has grabbed the reference, ctx is *NOT* going away until it gets around to
dropping that reference.
The fix is obvious - use percpu_ref_tryget_live() and treat failure as miss.
It's not costlier than what we currently do in normal case, it's safe to
call since freeing *is* delayed and it closes the race window - either
lookup_ioctx() comes before percpu_ref_kill() (in which case ctx->users
won't reach 0 until the caller of lookup_ioctx() drops it) or lookup_ioctx()
fails, ctx->users is unaffected and caller of lookup_ioctx() doesn't see
the object in question at all.
Cc: stable@kernel.org
Fixes: a6d7cff472e "fs/aio: Add explicit RCU grace period when freeing kioctx"
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Pull SCSI fix from James Bottomley:
"Eve of merge window fix: The original code was so bogus as to be
casting the wrong generic device to an rport and proceeding to take
actions based on the bogus values it found.
Fortunately it seems the location that is dereferenced always exists,
so the code hasn't oopsed yet, but it certainly annoys the memory
checkers"
* tag 'scsi-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi:
scsi: scsi_transport_srp: Fix shost to rport translation
Daniel Borkmann says:
====================
pull-request: bpf 2018-06-02
The following pull-request contains BPF updates for your *net* tree.
The main changes are:
1) BPF uapi fix in struct bpf_prog_info and struct bpf_map_info in
order to fix offsets on 32 bit archs.
This will have a minor merge conflict with net-next which has the
__u32 gpl_compatible:1 bitfield in struct bpf_prog_info at this
location. Resolution is to use the gpl_compatible member.
====================
Signed-off-by: David S. Miller <davem@davemloft.net>
Pull nds32 fixes from Greentime Hu:
"Bug fixes and build error fixes for nds32"
* tag 'nds32-for-linus-4.17-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/greentime/linux:
nds32: Fix compiler warning, Wstringop-overflow, in vdso.c
nds32: Disable local irq before calling cpu_dcache_wb_page in copy_user_highpage
nds32: Flush the cache of the page at vmaddr instead of kaddr in flush_anon_page
nds32: Correct flush_dcache_page function
nds32: Fix the unaligned access handler
nds32: Renaming the file for unaligned access
nds32: To fix a cache inconsistency issue by setting correct cacheability of NTC
nds32: To refine readability of INT_MASK_INITAIAL_VAL
nds32: Fix the virtual address may map too much range by tlbop issue.
nds32: Fix the allmodconfig build. To make sure CONFIG_CPU_LITTLE_ENDIAN is default y
nds32: Fix build failed because arch_trace_hardirqs_off is changed to trace_hardirqs_off.
nds32: Fix the unknown type u8 issue.
nds32: Fix the symbols undefined issue by exporting them.
nds32: Fix xfs_buf built failed by export invalidate_kernel_vmap_range and flush_kernel_vmap_range
nds32: Fix drivers/gpu/drm/udl/udl_fb.c building error by defining PAGE_SHARED
nds32: Fix building error of crypto/xor.c by adding xor.h
nds32: Fix building error when CONFIG_FREEZE is enabled.
nds32: lib: To use generic lib instead of libgcc to prevent the symbol undefined issue.
In the perf.data HEADER_CPUDESC feadure header we store first the number
of available CPUs in the system, then the number of CPUs at the time of
writing the header, not the other way around.
Reported-by: Thomas-Mich Richter <tmricht@linux.ibm.com>
Acked-by: Andi Kleen <ak@linux.intel.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: He Kuang <hekuang@huawei.com>
Cc: Hendrik Brueckner <brueckner@linux.vnet.ibm.com>
Cc: Jin Yao <yao.jin@linux.intel.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Kim Phillips <kim.phillips@arm.com>
Cc: Lakshman Annadorai <lakshmana@google.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Simon Que <sque@chromium.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Wang Nan <wangnan0@huawei.com>
Link: https://lkml.kernel.org/n/tip-j7o92acm2vnxjv70y4o3swoc@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>