This pull request want to land the analogix_dp driver into drm/bridge directory,
which reused the Exynos DP code, and add Rockchip DP support. And those
patches have been:
* 'drm-next-analogix-dp-v2' of github.com:yakir-Yang/linux:
drm: bridge: analogix/dp: Fix the possible dead lock in bridge disable time
drm: bridge: analogix/dp: add panel prepare/unprepare in suspend/resume time
drm: bridge: analogix/dp: add edid modes parse in get_modes method
drm: bridge: analogix/dp: move hpd detect to connector detect function
drm: bridge: analogix/dp: try force hpd after plug in lookup failed
drm: bridge: analogix/dp: add max link rate and lane count limit for RK3288
drm: bridge: analogix/dp: add some rk3288 special registers setting
dt-bindings: add document for rockchip variant of analogix_dp
drm: rockchip: dp: add rockchip platform dp driver
ARM: dts: exynos/dp: remove some properties that deprecated by analogix_dp driver
dt-bindings: add document for analogix display port driver
drm: bridge: analogix/dp: dynamic parse sync_pol & interlace & dynamic_range
drm: bridge: analogix/dp: remove duplicate configuration of link rate and link count
drm: bridge: analogix/dp: fix some obvious code style
drm: bridge: analogix/dp: rename register constants
drm/exynos: dp: rename implementation specific driver part
drm: bridge: analogix/dp: split exynos dp driver to bridge directory
Split the dp core driver from exynos directory to bridge directory,
and rename the core driver to analogix_dp_*, rename the platform
code to exynos_dp.
Beside the new analogix_dp driver would export six hooks.
"analogix_dp_bind()" and "analogix_dp_unbind()"
"analogix_dp_suspned()" and "analogix_dp_resume()"
"analogix_dp_detect()" and "analogix_dp_get_modes()"
The bind/unbind symbols is used for analogix platform driver to connect
with analogix_dp core driver. And the detect/get_modes is used for analogix
platform driver to init the connector.
They reason why connector need register in helper driver is rockchip drm
haven't implement the atomic API, but Exynos drm have implement it, so
there would need two different connector helper functions, that's why we
leave the connector register in helper driver.
Acked-by: Inki Dae <inki.dae@samsung.com>
Tested-by: Caesar Wang <wxt@rock-chips.com>
Tested-by: Douglas Anderson <dianders@chromium.org>
Tested-by: Heiko Stuebner <heiko@sntech.de>
Tested-by: Javier Martinez Canillas <javier@osg.samsung.com>
Signed-off-by: Yakir Yang <ykk@rock-chips.com>
Signed-off-by: Heiko Stuebner <heiko@sntech.de>
Pull core kernel fixes from Ingo Molnar:
"This contains the nohz/atomic cleanup/fix for the fetch_or() ugliness
you noted during the original nohz pull request, plus there's also
misc fixes:
- fix liblockdep build bug
- fix uapi header build bug
- print more lockdep hash collision info to help debug recent reports
of hash collisions
- update MAINTAINERS email address"
* 'core-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
MAINTAINERS: Update my email address
locking/lockdep: Print chain_key collision information
uapi/linux/stddef.h: Provide __always_inline to userspace headers
tools/lib/lockdep: Fix unsupported 'basename -s' in run_tests.sh
locking/atomic, sched: Unexport fetch_or()
timers/nohz: Convert tick dependency mask to atomic_t
locking/atomic: Introduce atomic_fetch_or()
Pull SCSI target fixes from Nicholas Bellinger:
"This includes fixes from HCH for -rc1 configfs default_groups
conversion changes that ended up breaking some iscsi-target
default_groups, along with Sagi's ib_drain_qp() conversion for
iser-target to use the common caller now available to RDMA kernel
consumers in v4.6+ code"
* git://git.kernel.org/pub/scm/linux/kernel/git/nab/target-pending:
target: add a new add_wwn_groups fabrics method
target: initialize the nacl base CIT begfore init_nodeacl
target: remove ->fabric_cleanup_nodeacl
iser-target: Use ib_drain_qp
Pull configfs fix from Christoph Hellwig:
"A trivial fix to the recently introduced binary attribute helper
macros"
* tag 'configfs-for-linus-2' of git://git.infradead.org/users/hch/configfs:
configfs: fix CONFIGFS_BIN_ATTR_[RW]O definitions
Pull networking fixes from David Miller:
1) Missing device reference in IPSEC input path results in crashes
during device unregistration. From Subash Abhinov Kasiviswanathan.
2) Per-queue ISR register writes not being done properly in macb
driver, from Cyrille Pitchen.
3) Stats accounting bugs in bcmgenet, from Patri Gynther.
4) Lightweight tunnel's TTL and TOS were swapped in netlink dumps, from
Quentin Armitage.
5) SXGBE driver has off-by-one in probe error paths, from Rasmus
Villemoes.
6) Fix race in save/swap/delete options in netfilter ipset, from
Vishwanath Pai.
7) Ageing time of bridge not set properly when not operating over a
switchdev device. Fix from Haishuang Yan.
8) Fix GRO regression wrt nested FOU/GUE based tunnels, from Alexander
Duyck.
9) IPV6 UDP code bumps wrong stats, from Eric Dumazet.
10) FEC driver should only access registers that actually exist on the
given chipset, fix from Fabio Estevam.
* git://git.kernel.org/pub/scm/linux/kernel/git/davem/net: (73 commits)
net: mvneta: fix changing MTU when using per-cpu processing
stmmac: fix MDIO settings
Revert "stmmac: Fix 'eth0: No PHY found' regression"
stmmac: fix TX normal DESC
net: mvneta: use cache_line_size() to get cacheline size
net: mvpp2: use cache_line_size() to get cacheline size
net: mvpp2: fix maybe-uninitialized warning
tun, bpf: fix suspicious RCU usage in tun_{attach, detach}_filter
net: usb: cdc_ncm: adding Telit LE910 V2 mobile broadband card
rtnl: fix msg size calculation in if_nlmsg_size()
fec: Do not access unexisting register in Coldfire
net: mvneta: replace MVNETA_CPU_D_CACHE_LINE_SIZE with L1_CACHE_BYTES
net: mvpp2: replace MVPP2_CPU_D_CACHE_LINE_SIZE with L1_CACHE_BYTES
net: dsa: mv88e6xxx: Clear the PDOWN bit on setup
net: dsa: mv88e6xxx: Introduce _mv88e6xxx_phy_page_{read, write}
bpf: make padding in bpf_tunnel_key explicit
ipv6: udp: fix UDP_MIB_IGNOREDMULTI updates
bnxt_en: Fix ethtool -a reporting.
bnxt_en: Fix typo in bnxt_hwrm_set_pause_common().
bnxt_en: Implement proper firmware message padding.
...
Page isolation has not failed if the fin pfn extends beyond the end pfn
and test_pages_isolated checks this correctly. Fix the tracepoint to
report the same result as the actual check function.
Signed-off-by: Lucas Stach <l.stach@pengutronix.de>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Joonsoo Kim <js1304@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Initially the phy_bus_name was added to manipulate the
driver name but it was recently just used to manage the
fixed-link and then to take some decision at run-time.
So the patch uses the is_pseudo_fixed_link and removes
the phy_bus_name variable not necessary anymore.
The driver can manage the mdio registration by using phy-handle,
dwmac-mdio and own parameter e.g. snps,phy-addr.
This patch takes care about all these possible configurations
and fixes the mdio registration in case of there is a real
transceiver or a switch (that needs to be managed by using
fixed-link).
Signed-off-by: Giuseppe Cavallaro <peppe.cavallaro@st.com>
Reviewed-by: Andreas Färber <afaerber@suse.de>
Tested-by: Frank Schäfer <fschaefer.oss@googlemail.com>
Cc: Gabriel Fernandez <gabriel.fernandez@linaro.org>
Cc: Dinh Nguyen <dinh.linux@gmail.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Phil Reid <preid@electromag.com.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
Sasha Levin reported a suspicious rcu_dereference_protected() warning
found while fuzzing with trinity that is similar to this one:
[ 52.765684] net/core/filter.c:2262 suspicious rcu_dereference_protected() usage!
[ 52.765688] other info that might help us debug this:
[ 52.765695] rcu_scheduler_active = 1, debug_locks = 1
[ 52.765701] 1 lock held by a.out/1525:
[ 52.765704] #0: (rtnl_mutex){+.+.+.}, at: [<ffffffff816a64b7>] rtnl_lock+0x17/0x20
[ 52.765721] stack backtrace:
[ 52.765728] CPU: 1 PID: 1525 Comm: a.out Not tainted 4.5.0+ #264
[...]
[ 52.765768] Call Trace:
[ 52.765775] [<ffffffff813e488d>] dump_stack+0x85/0xc8
[ 52.765784] [<ffffffff810f2fa5>] lockdep_rcu_suspicious+0xd5/0x110
[ 52.765792] [<ffffffff816afdc2>] sk_detach_filter+0x82/0x90
[ 52.765801] [<ffffffffa0883425>] tun_detach_filter+0x35/0x90 [tun]
[ 52.765810] [<ffffffffa0884ed4>] __tun_chr_ioctl+0x354/0x1130 [tun]
[ 52.765818] [<ffffffff8136fed0>] ? selinux_file_ioctl+0x130/0x210
[ 52.765827] [<ffffffffa0885ce3>] tun_chr_ioctl+0x13/0x20 [tun]
[ 52.765834] [<ffffffff81260ea6>] do_vfs_ioctl+0x96/0x690
[ 52.765843] [<ffffffff81364af3>] ? security_file_ioctl+0x43/0x60
[ 52.765850] [<ffffffff81261519>] SyS_ioctl+0x79/0x90
[ 52.765858] [<ffffffff81003ba2>] do_syscall_64+0x62/0x140
[ 52.765866] [<ffffffff817d563f>] entry_SYSCALL64_slow_path+0x25/0x25
Same can be triggered with PROVE_RCU (+ PROVE_RCU_REPEATEDLY) enabled
from tun_attach_filter() when user space calls ioctl(tun_fd, TUN{ATTACH,
DETACH}FILTER, ...) for adding/removing a BPF filter on tap devices.
Since the fix in f91ff5b9ff ("net: sk_{detach|attach}_filter() rcu
fixes") sk_attach_filter()/sk_detach_filter() now dereferences the
filter with rcu_dereference_protected(), checking whether socket lock
is held in control path.
Since its introduction in 9940516259 ("tun: socket filter support"),
tap filters are managed under RTNL lock from __tun_chr_ioctl(). Thus the
sock_owned_by_user(sk) doesn't apply in this specific case and therefore
triggers the false positive.
Extend the BPF API with __sk_attach_filter()/__sk_detach_filter() pair
that is used by tap filters and pass in lockdep_rtnl_is_held() for the
rcu_dereference_protected() checks instead.
Reported-by: Sasha Levin <sasha.levin@oracle.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
We need to have the WWN fully initialized before addig default groups to it,
so add a new method to add these groups after the WWN has been initialized.
Also remove the default groups in the core while we're at it.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
Instead we can clean up the list of default ACLs in core code.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
Make the 2 byte padding in struct bpf_tunnel_key between tunnel_ttl
and tunnel_label members explicit. No issue has been observed, and
gcc/llvm does padding for the old struct already, where tunnel_label
was not yet present, so the current code works, but since it's part
of uapi, make sure we don't introduce holes in structs.
Therefore, add tunnel_ext that we can use generically in future
(f.e. to flag OAM messages for backends, etc). Also add the offset
to the compat tests to be sure should some compilers not padd the
tail of the old version of bpf_tunnel_key.
Fixes: 4018ab1875 ("bpf: support flow label for bpf_skb_{set, get}_tunnel_key")
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
This allows us to ditch a ton of ugly #ifdefs from a bunch of drm modeset
drivers.
v2: Make the dummy function actually return a sane value, spotted by
Ville.
v3: Because the patch is still in limbo there's no more drivers to
convert, noticed by Emil.
v4: Rebase once more, because hooray. I'll just go ahead an apply this
one later on to drm-misc.
Cc: Emil Velikov <emil.l.velikov@gmail.com>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: Emil Velikov <emil.l.velikov@gmail.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
This patch functionally reverts:
5fd7a09cfb ("atomic: Export fetch_or()")
During the merge Linus observed that the generic version of fetch_or()
was messy:
" This makes the ugly "fetch_or()" macro that the scheduler used
internally a new generic helper, and does a bad job at it. "
e23604edac Merge branch 'timers-nohz-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Now that we have introduced atomic_fetch_or(), fetch_or() is only used
by the scheduler in order to deal with thread_info flags which type
can vary across architectures.
Lets confine fetch_or() back to the scheduler so that we encourage
future users to use the more robust and well typed atomic_t version
instead.
While at it, fetch_or() gets robustified, pasting improvements from a
previous patch by Ingo Molnar that avoids needless expression
re-evaluations in the loop.
Reported-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1458830281-4255-4-git-send-email-fweisbec@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This fix adds a new reference counter (ref_netlink) for the struct ip_set.
The other reference counter (ref) can be swapped out by ip_set_swap and we
need a separate counter to keep track of references for netlink events
like dump. Using the same ref counter for dump causes a race condition
which can be demonstrated by the following script:
ipset create hash_ip1 hash:ip family inet hashsize 1024 maxelem 500000 \
counters
ipset create hash_ip2 hash:ip family inet hashsize 300000 maxelem 500000 \
counters
ipset create hash_ip3 hash:ip family inet hashsize 1024 maxelem 500000 \
counters
ipset save &
ipset swap hash_ip3 hash_ip2
ipset destroy hash_ip3 /* will crash the machine */
Swap will exchange the values of ref so destroy will see ref = 0 instead of
ref = 1. With this fix in place swap will not succeed because ipset save
still has ref_netlink on the set (ip_set_swap doesn't swap ref_netlink).
Both delete and swap will error out if ref_netlink != 0 on the set.
Note: The changes to *_head functions is because previously we would
increment ref whenever we called these functions, we don't do that
anymore.
Reviewed-by: Joshua Hunt <johunt@akamai.com>
Signed-off-by: Vishwanath Pai <vpai@akamai.com>
Signed-off-by: Jozsef Kadlecsik <kadlec@blackhole.kfki.hu>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Pull Ceph updates from Sage Weil:
"There is quite a bit here, including some overdue refactoring and
cleanup on the mon_client and osd_client code from Ilya, scattered
writeback support for CephFS and a pile of bug fixes from Zheng, and a
few random cleanups and fixes from others"
[ I already decided not to pull this because of it having been rebased
recently, but ended up changing my mind after all. Next time I'll
really hold people to it. Oh well. - Linus ]
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/sage/ceph-client: (34 commits)
libceph: use KMEM_CACHE macro
ceph: use kmem_cache_zalloc
rbd: use KMEM_CACHE macro
ceph: use lookup request to revalidate dentry
ceph: kill ceph_get_dentry_parent_inode()
ceph: fix security xattr deadlock
ceph: don't request vxattrs from MDS
ceph: fix mounting same fs multiple times
ceph: remove unnecessary NULL check
ceph: avoid updating directory inode's i_size accidentally
ceph: fix race during filling readdir cache
libceph: use sizeof_footer() more
ceph: kill ceph_empty_snapc
ceph: fix a wrong comparison
ceph: replace CURRENT_TIME by current_fs_time()
ceph: scattered page writeback
libceph: add helper that duplicates last extent operation
libceph: enable large, variable-sized OSD requests
libceph: osdc->req_mempool should be backed by a slab pool
libceph: make r_request msg_size calculation clearer
...
Pull NTB bug fixes from Jon Mason:
"NTB bug fixes for tasklet from spinning forever, link errors,
translation window setup, NULL ptr dereference, and ntb-perf errors.
Also, a modification to the driver API that makes _addr functions
optional"
* tag 'ntb-4.6' of git://github.com/jonmason/ntb:
NTB: Remove _addr functions from ntb_hw_amd
NTB: Make _addr functions optional in the API
NTB: Fix incorrect clean up routine in ntb_perf
NTB: Fix incorrect return check in ntb_perf
ntb: fix possible NULL dereference
ntb: add missing setup of translation window
ntb: stop link work when we do not have memory
ntb: stop tasklet from spinning forever during shutdown.
ntb: perf test: fix address space confusion
Pull more SCSI updates from James Bottomley:
"The only new stuff which missed the first pull request is an update to
the UFS driver.
The rest is an assortment of bug fixes and minor tweaks which appeared
recently (some are fixes for recent code and some are stuff spotted
recently by the checkers or the new gcc-6 compiler [most of Arnd's
stuff])"
* tag 'scsi-misc' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi: (32 commits)
scsi_common: do not clobber fixed sense information
scsi: ufs: select CONFIG_NLS
scsi: fc: use get/put_unaligned64 for wwn access
fnic: move printk()s outside of the critical code section.
qla2xxx: avoid maybe_uninitialized warning
megaraid_sas: add missing curly braces in ioctl handler
lpfc: fix misleading indentation
scsi_transport_sas: add 'scsi_target_id' sysfs attribute
scsi_dh_alua: uninitialized variable in alua_check_vpd()
scsi: ufs-qcom: add printouts of testbus debug registers
scsi: ufs-qcom: enable/disable the device ref clock
scsi: ufs-qcom: set PA_Local_TX_LCC_Enable before link startup
scsi: ufs: add device quirk delay before putting UFS rails in LPM
scsi: ufs: fix leakage during link off state
scsi: ufs: tune UniPro parameters to optimize hibern8 exit time
scsi: ufs: handle non spec compliant bkops behaviour by device
scsi: ufs: add retry for query descriptors
scsi: ufs: add error recovery after DL NAC error
scsi: ufs: make error handling bit faster
scsi: ufs: disable vccq if it's not needed by UFS device
...
Implement the stack depot and provide CONFIG_STACKDEPOT. Stack depot
will allow KASAN store allocation/deallocation stack traces for memory
chunks. The stack traces are stored in a hash table and referenced by
handles which reside in the kasan_alloc_meta and kasan_free_meta
structures in the allocated memory chunks.
IRQ stack traces are cut below the IRQ entry point to avoid unnecessary
duplication.
Right now stackdepot support is only enabled in SLAB allocator. Once
KASAN features in SLAB are on par with those in SLUB we can switch SLUB
to stackdepot as well, thus removing the dependency on SLUB stack
bookkeeping, which wastes a lot of memory.
This patch is based on the "mm: kasan: stack depots" patch originally
prepared by Dmitry Chernenkov.
Joonsoo has said that he plans to reuse the stackdepot code for the
mm/page_owner.c debugging facility.
[akpm@linux-foundation.org: s/depot_stack_handle/depot_stack_handle_t]
[aryabinin@virtuozzo.com: comment style fixes]
Signed-off-by: Alexander Potapenko <glider@google.com>
Signed-off-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Andrey Konovalov <adech.fo@gmail.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Konstantin Serebryany <kcc@google.com>
Cc: Dmitry Chernenkov <dmitryc@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
KASAN needs to know whether the allocation happens in an IRQ handler.
This lets us strip everything below the IRQ entry point to reduce the
number of unique stack traces needed to be stored.
Move the definition of __irq_entry to <linux/interrupt.h> so that the
users don't need to pull in <linux/ftrace.h>. Also introduce the
__softirq_entry macro which is similar to __irq_entry, but puts the
corresponding functions to the .softirqentry.text section.
Signed-off-by: Alexander Potapenko <glider@google.com>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Andrey Konovalov <adech.fo@gmail.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Konstantin Serebryany <kcc@google.com>
Cc: Dmitry Chernenkov <dmitryc@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
"oom, oom_reaper: disable oom_reaper for oom_kill_allocating_task" tried
to protect oom_reaper_list using MMF_OOM_KILLED flag. But we can do it
by simply checking tsk->oom_reaper_list != NULL.
Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Signed-off-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Tetsuo has reported that oom_kill_allocating_task=1 will cause
oom_reaper_list corruption because oom_kill_process doesn't follow
standard OOM exclusion (aka ignores TIF_MEMDIE) and allows to enqueue
the same task multiple times - e.g. by sacrificing the same child
multiple times.
This patch fixes the issue by introducing a new MMF_OOM_KILLED mm flag
which is set in oom_kill_process atomically and oom reaper is disabled
if the flag was already set.
Signed-off-by: Michal Hocko <mhocko@suse.com>
Reported-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: David Rientjes <rientjes@google.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Rik van Riel <riel@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
wake_oom_reaper has allowed only 1 oom victim to be queued. The main
reason for that was the simplicity as other solutions would require some
way of queuing. The current approach is racy and that was deemed
sufficient as the oom_reaper is considered a best effort approach to
help with oom handling when the OOM victim cannot terminate in a
reasonable time. The race could lead to missing an oom victim which can
get stuck
out_of_memory
wake_oom_reaper
cmpxchg // OK
oom_reaper
oom_reap_task
__oom_reap_task
oom_victim terminates
atomic_inc_not_zero // fail
out_of_memory
wake_oom_reaper
cmpxchg // fails
task_to_reap = NULL
This race requires 2 OOM invocations in a short time period which is not
very likely but certainly not impossible. E.g. the original victim
might have not released a lot of memory for some reason.
The situation would improve considerably if wake_oom_reaper used a more
robust queuing. This is what this patch implements. This means adding
oom_reaper_list list_head into task_struct (eat a hole before embeded
thread_struct for that purpose) and a oom_reaper_lock spinlock for
queuing synchronization. wake_oom_reaper will then add the task on the
queue and oom_reaper will dequeue it.
Signed-off-by: Michal Hocko <mhocko@suse.com>
Cc: Vladimir Davydov <vdavydov@virtuozzo.com>
Cc: Andrea Argangeli <andrea@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
When oom_reaper manages to unmap all the eligible vmas there shouldn't
be much of the freable memory held by the oom victim left anymore so it
makes sense to clear the TIF_MEMDIE flag for the victim and allow the
OOM killer to select another task.
The lack of TIF_MEMDIE also means that the victim cannot access memory
reserves anymore but that shouldn't be a problem because it would get
the access again if it needs to allocate and hits the OOM killer again
due to the fatal_signal_pending resp. PF_EXITING check. We can safely
hide the task from the OOM killer because it is clearly not a good
candidate anymore as everyhing reclaimable has been torn down already.
This patch will allow to cap the time an OOM victim can keep TIF_MEMDIE
and thus hold off further global OOM killer actions granted the oom
reaper is able to take mmap_sem for the associated mm struct. This is
not guaranteed now but further steps should make sure that mmap_sem for
write should be blocked killable which will help to reduce such a lock
contention. This is not done by this patch.
Note that exit_oom_victim might be called on a remote task from
__oom_reap_task now so we have to check and clear the flag atomically
otherwise we might race and underflow oom_victims or wake up waiters too
early.
Signed-off-by: Michal Hocko <mhocko@suse.com>
Suggested-by: Johannes Weiner <hannes@cmpxchg.org>
Suggested-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: Andrea Argangeli <andrea@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Rik van Riel <riel@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This patch (of 5):
This is based on the idea from Mel Gorman discussed during LSFMM 2015
and independently brought up by Oleg Nesterov.
The OOM killer currently allows to kill only a single task in a good
hope that the task will terminate in a reasonable time and frees up its
memory. Such a task (oom victim) will get an access to memory reserves
via mark_oom_victim to allow a forward progress should there be a need
for additional memory during exit path.
It has been shown (e.g. by Tetsuo Handa) that it is not that hard to
construct workloads which break the core assumption mentioned above and
the OOM victim might take unbounded amount of time to exit because it
might be blocked in the uninterruptible state waiting for an event (e.g.
lock) which is blocked by another task looping in the page allocator.
This patch reduces the probability of such a lockup by introducing a
specialized kernel thread (oom_reaper) which tries to reclaim additional
memory by preemptively reaping the anonymous or swapped out memory owned
by the oom victim under an assumption that such a memory won't be needed
when its owner is killed and kicked from the userspace anyway. There is
one notable exception to this, though, if the OOM victim was in the
process of coredumping the result would be incomplete. This is
considered a reasonable constrain because the overall system health is
more important than debugability of a particular application.
A kernel thread has been chosen because we need a reliable way of
invocation so workqueue context is not appropriate because all the
workers might be busy (e.g. allocating memory). Kswapd which sounds
like another good fit is not appropriate as well because it might get
blocked on locks during reclaim as well.
oom_reaper has to take mmap_sem on the target task for reading so the
solution is not 100% because the semaphore might be held or blocked for
write but the probability is reduced considerably wrt. basically any
lock blocking forward progress as described above. In order to prevent
from blocking on the lock without any forward progress we are using only
a trylock and retry 10 times with a short sleep in between. Users of
mmap_sem which need it for write should be carefully reviewed to use
_killable waiting as much as possible and reduce allocations requests
done with the lock held to absolute minimum to reduce the risk even
further.
The API between oom killer and oom reaper is quite trivial.
wake_oom_reaper updates mm_to_reap with cmpxchg to guarantee only
NULL->mm transition and oom_reaper clear this atomically once it is done
with the work. This means that only a single mm_struct can be reaped at
the time. As the operation is potentially disruptive we are trying to
limit it to the ncessary minimum and the reaper blocks any updates while
it operates on an mm. mm_struct is pinned by mm_count to allow parallel
exit_mmap and a race is detected by atomic_inc_not_zero(mm_users).
Signed-off-by: Michal Hocko <mhocko@suse.com>
Suggested-by: Oleg Nesterov <oleg@redhat.com>
Suggested-by: Mel Gorman <mgorman@suse.de>
Acked-by: Mel Gorman <mgorman@suse.de>
Acked-by: David Rientjes <rientjes@google.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Andrea Argangeli <andrea@kernel.org>
Cc: Rik van Riel <riel@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
