- 17 Nov, 2016 1 commit
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Michael Holzheu authored
Signed-off-by: Michael Holzheu <holzheu@linux.vnet.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
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- 15 Nov, 2016 1 commit
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Martin Schwidefsky authored
Move the last two architecture specific fields from the thread_info structure to the thread_struct. All that is left in thread_info is the flags field. Reviewed-by: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
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- 11 Nov, 2016 6 commits
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Martin Schwidefsky authored
The user_timer and system_timer fields are used for the per-thread cputime accounting code. The access to these values is simpler if they are moved to the thread_struct as the task_thread_info(tsk) indirection is not needed anymore. Reviewed-by: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
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Martin Schwidefsky authored
The system_call field in thread_info structure is used by the signal code to store the number of the current system call while the debugger interacts with its inferior. A better location for the system_call field is with the other debugger related information in the thread_struct. Reviewed-by: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
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Heiko Carstens authored
This is the s390 variant of commit 15f4eae7 ("x86: Move thread_info into task_struct"). Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
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Martin Schwidefsky authored
Convert s390 to use a field in the struct lowcore for the CPU preemption count. It is a bit cheaper to access a lowcore field compared to a thread_info variable and it removes the depencency on a task related structure. bloat-o-meter on the vmlinux image for the default configuration (CONFIG_PREEMPT_NONE=y) reports a small reduction in text size: add/remove: 0/0 grow/shrink: 18/578 up/down: 228/-5448 (-5220) A larger improvement is achieved with the default configuration but with CONFIG_PREEMPT=y and CONFIG_DEBUG_PREEMPT=n: add/remove: 2/6 grow/shrink: 59/4477 up/down: 1618/-228762 (-227144) Reviewed-by: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
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Martin Schwidefsky authored
Replace the bitops specific atomic update code by the functions from atomic_ops.h. This saves a few lines of non-trivial code. Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
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Martin Schwidefsky authored
Rework atomic.h to make the low level functions avaible for use in other headers without using atomic_t, e.g. in bitops.h. Reviewed-by: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
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- 08 Nov, 2016 1 commit
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Masahiro Yamada authored
The dependency between the object and the source is handled by scripts/Makefile.host, so only "hostprogs-y += gen_facilities" is fine. Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com> Acked-by: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
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- 07 Nov, 2016 2 commits
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Masahiro Yamada authored
We generally expect headers in arch/$(ARCH)/include/asm directory are included from kernel sources, but facilities_src.h is not; it is included from the arch/s390/tools/gen_facilities.c tool. There is no reason to expose this header to the public include path. Furthermore, facilities_src.h makes sure to be included only from gen_facilities.c by the following: #ifndef S390_GEN_FACILITIES_C #error "This file can only be included by gen_facilities.c" #endif This check can be removed by merging the two files. Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com> Acked-by: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
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Masahiro Yamada authored
The header facilities_src.h is only included from gen_facilities.c and the tool is compiled with the following extra options: HOSTCFLAGS_gen_facilities.o += -Wall $(LINUXINCLUDE) Please note $(LINUXINCLUDE) is expanded into build options including: -include $(srctree)/include/linux/kconfig.h So, the Makefile always forces the tool to include kconfig.h, i.e., the #include <linux/kconfig.h> directive in the header is redundant. Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com> Acked-by: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
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- 31 Oct, 2016 9 commits
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Paul Gortmaker authored
The Kconfig currently controlling compilation of this code is: arch/s390/Kconfig:config S390_GUEST arch/s390/Kconfig: def_bool y ...meaning that it currently is not being built as a module by anyone. Lets remove the modular code that is essentially orphaned, so that when reading the driver there is no doubt it is builtin-only. Since module_init translates to device_initcall in the non-modular case, the init ordering remains unchanged with this commit. Also note that MODULE_DEVICE_TABLE is a no-op for non-modular code. We replace module.h with moduleparam.h since the file does declare some module_param() and leaving that as-is is currently the easiest way to remain compatible with existing boot arg use cases. Cc: Christian Borntraeger <borntraeger@de.ibm.com> Cc: Cornelia Huck <cornelia.huck@de.ibm.com> Cc: linux-s390@vger.kernel.org Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com> Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
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Paul Gortmaker authored
The Kconfig currently controlling compilation of this code is: drivers/pci/hotplug/Kconfig:config HOTPLUG_PCI_S390 drivers/pci/hotplug/Kconfig: bool "System z PCI Hotplug Support" ...meaning that it currently is not being built as a module by anyone. Lets remove the couple traces of modular infrastructure use, so that when reading the driver there is no doubt it is builtin-only. We also delete the MODULE_LICENSE tag etc. since all that information was (or is now) contained at the top of the file in the comments. We don't exchange module.h for init.h or export.h since the file does not contain any initcalls or EXPORT of symbols. Cc: Sebastian Ott <sebott@linux.vnet.ibm.com> Cc: Gerald Schaefer <gerald.schaefer@de.ibm.com> Cc: Bjorn Helgaas <bhelgaas@google.com> Cc: linux-s390@vger.kernel.org Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com> Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
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Paul Gortmaker authored
The Makefile currently controlling compilation of this code is obj-y meaning that it currently is not being built as a module by anyone. Lets remove the couple traces of modular infrastructure use, so that when reading the driver there is no doubt it is builtin-only. Since module_init translates to device_initcall in the non-modular case, the init ordering remains unchanged with this commit. We replace module.h with init.h and export.h since the file does export some symbols. Cc: linux-s390@vger.kernel.org Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com> Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
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Paul Gortmaker authored
The Kconfig currently controlling compilation of this code is: arch/s390/Kconfig:config S390_HYPFS_FS arch/s390/Kconfig: def_bool y ...meaning that it currently is not being built as a module by anyone. Lets remove the couple traces of modular infrastructure use, so that when reading the driver there is no doubt it is builtin-only. Since module_init translates to device_initcall in the non-modular case, the init ordering remains unchanged with this commit. Also note that MODULE_ALIAS is a no-op for non-modular code. We also delete the MODULE_LICENSE tag etc. since all that information was (or is now) contained at the top of the file in the comments. Build testing indicated the presence of module.h was masking an implicit include of kobject.h, hence the addition of that. Cc: linux-s390@vger.kernel.org Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com> Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
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Paul Gortmaker authored
The Makefile currently controlling compilation of this code is obj-y, meaning that it currently is not being built as a module by anyone. Lets remove the couple traces of modular infrastructure, so that when reading the driver there is no doubt it is builtin-only. Since module_init translates to device_initcall in the non-modular case, the init ordering remains unchanged with this commit. Cc: linux-s390@vger.kernel.org Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com> Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
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Paul Gortmaker authored
The Kconfig currently controlling compilation of this code is: drivers/s390/char/Kconfig:config SCLP_TTY drivers/s390/char/Kconfig: def_bool y ...meaning that it currently is not being built as a module by anyone. Lets remove the couple traces of modular infrastructure use, so that when reading the driver there is no doubt it is builtin-only. Since module_init translates to device_initcall in the non-modular case, the init ordering remains unchanged with this commit. We don't replace module.h with init.h since the file already has that. Cc: Peter Oberparleiter <oberpar@linux.vnet.ibm.com> Cc: linux-s390@vger.kernel.org Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com> Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
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Paul Gortmaker authored
The Kconfig currently controlling compilation of this code is: drivers/s390/char/Kconfig:config TN3215 drivers/s390/char/Kconfig: def_bool y ...meaning that it currently is not being built as a module by anyone. Lets remove the modular code that is essentially orphaned, so that when reading the driver there is no doubt it is builtin-only. Since module_init translates to device_initcall in the non-modular case, the init ordering remains unchanged with this commit. We don't replace module.h with init.h since the file already has that. Cc: linux-s390@vger.kernel.org Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com> Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
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Paul Gortmaker authored
The Kconfig currently controlling compilation of this code is: arch/s390/Kconfig:config CRASH_DUMP arch/s390/Kconfig: bool "kernel crash dumps" ...meaning that it currently is not being built as a module by anyone. Lets remove the modular code that is essentially orphaned, so that when reading the driver there is no doubt it is builtin-only. Since module_init wasn't even being used by this file, the init ordering remains unchanged with this commit. We also delete the MODULE_LICENSE tag etc. since all that information was (or is now) contained at the top of the file in the comments. We don't replace module.h with init.h since the file already has that. Cc: linux-s390@vger.kernel.org Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com> Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
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Paul Gortmaker authored
The Makefile currently controlling compilation of this code is: obj-y += airq.o blacklist.o chsc.o cio.o css.o chp.o idset.o isc.o \ fcx.o itcw.o crw.o ccwreq.o trace.o ioasm.o ccw_device-objs += device.o device_fsm.o device_ops.o ccw_device-objs += device_id.o device_pgid.o device_status.o obj-y += ccw_device.o cmf.o ...meaning that the files here are not being built as modular. Lets remove the couple traces of modular infrastructure use, so that when reading the code there is no doubt it is builtin-only. Since module_init translates to device_initcall in the non-modular case, the init ordering remains unchanged with this commit. Also note that MODULE_DEVICE_TABLE is a no-op for non-modular code. We delete the MODULE_LICENSE tag etc. since all that information was (or is now) contained at the top of the file in the comments. We replace module.h with export.h where the file does export some symbols. Cc: Sebastian Ott <sebott@linux.vnet.ibm.com> Cc: Peter Oberparleiter <oberpar@linux.vnet.ibm.com> Cc: Cornelia Huck <cornelia.huck@de.ibm.com> Cc: Arnd Bergmann <arndb@de.ibm.com> Cc: linux-s390@vger.kernel.org Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com> Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
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- 28 Oct, 2016 20 commits
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Jan Höppner authored
The function dasd_ro_store() calls set_disk_ro() to set the device in question read-only. Since set_disk_ro() might sleep, we can't call it while holding a lock. However, we also can't simply check if the device, block, and gdp references are valid before we call set_disk_ro() because an offline processing might have been started in the meanwhile which will destroy those references. In order to reliably call set_disk_ro() we have to ensure several things: - Still check validity of the mentioned references but additionally check if offline processing is running and bail out accordingly. Also, do this while holding the device lock. - To ensure that the block device is still safe after the lock, increase the open_count while still holding the device lock. Reviewed-by: Stefan Haberland <sth@linux.vnet.ibm.com> Signed-off-by: Jan Höppner <hoeppner@linux.vnet.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
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Jan Höppner authored
The reference to a device in question may get lost when the extended error reporting (EER) attribute is being enabled/disabled while the device is set offline at the same time. This is due to missing refcounting and incorrect locking. Fix this by the following: - In dasd_eer_store() get the device directly and handle the refcount accordingly. - Move the lock in dasd_eer_enable() up so we can ensure safe processing. - Check if the device is being set offline and return with -EBUSY if so. - While at it, change the return code from -EPERM to -EMEDIUMTYPE as suggested by a FIXME, since that is what we're actually checking. Reviewed-by: Stefan Haberland <sth@linux.vnet.ibm.com> Signed-off-by: Jan Höppner <hoeppner@linux.vnet.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
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Jan Höppner authored
Before we set a device offline, the open_count for the block device is checked and certain flags are checked and set as well. However, this is all done without holding any lock. Potentially, if the open_count was checked but the DASD_FLAG_OFFLINE wasn't set yet, a different process might want to increase the open_count depending on whether DASD_FLAG_OFFLINE is set or not in the meanwhile. This is quite racy and can lead to the loss of the device for that process and subsequently lead to a panic. Fix this by checking the open_count and setting the offline flags while holding the ccwdev lock. Reviewed-by: Stefan Haberland <sth@linux.vnet.ibm.com> Signed-off-by: Jan Höppner <hoeppner@linux.vnet.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
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Jan Höppner authored
When setting certain attributes, we actually set the according feature flag. Do this by using dasd_set_feature() at a few occurrences and remove duplicate code. In dasd_set_feature() dasd_find_busid() is used to retrieve the devmap for the device in question. Combined with the change above, this would require the device to be set online at least once so that a devmap is being created. Change that by using dasd_devmap_from_cdev() instead, which uses dasd_find_busid() first and will create a devmap accordingly if there is none yet. Reviewed-by: Stefan Haberland <sth@linux.vnet.ibm.com> Signed-off-by: Jan Höppner <hoeppner@linux.vnet.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
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Jan Höppner authored
simple_strtoul() has been marked obsolete for quite some time now. Replace a few last occurrences with kstrtouint(). Reviewed-by: Stefan Haberland <sth@linux.vnet.ibm.com> Signed-off-by: Jan Höppner <hoeppner@linux.vnet.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
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Dong Jia Shi authored
Clean up DEV_STATE_SENSE_PGID related code, since it's not used anymore. Everything related to path verification is handled within DEV_STATE_VERIFY. Signed-off-by: Dong Jia Shi <bjsdjshi@linux.vnet.ibm.com> Acked-by: Sebastian Ott <sebott@linux.vnet.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
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Martin Schwidefsky authored
On STP sync events the TOD clock will jump in time, either forward or backward. The TOD clocksource claims to be continuous but in case of an STP sync with a negative offset it is not. Subtract the offset injected by the STP sync check from the result of the TOD clocksource to make it continuous again. Add code to drift the offset towards zero with a fixed rate, steering 1 second in ~9 hours. Suggested-by: David Hildenbrand <dahi@linux.vnet.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
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Martin Schwidefsky authored
The last_update_clock time stamp in the lowcore should be adjusted by the TOD clock delta that is created by the clock synchronization. Otherwise the calculation of the steal time will be incorrect. Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
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Martin Schwidefsky authored
Merge clock_sync_cpu into stp_sync_clock and split out the update of the global and per-CPU clock fields into clock_sync_global and clock_sync_local. Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
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Jan Höppner authored
block->request_queue is used many times in dasd_setup_queue. Define a separate variable to increase readability a bit and to make it better reusable. Reviewed-by: Stefan Haberland <sth@linux.vnet.ibm.com> Signed-off-by: Jan Höppner <hoeppner@linux.vnet.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
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Jan Höppner authored
Currently the block queue value max_segments is set to -1L, which is then implicitly casted to unsigned short in blk_queue_max_segments. This results in 65535 (64k) max_segments. Even though the resulting value is correct, setting it implicitly using -1L is rather confusing. Set the value explicitly using the USHRT_MAX macro instead. Reviewed-by: Stefan Haberland <sth@linux.vnet.ibm.com> Signed-off-by: Jan Höppner <hoeppner@linux.vnet.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
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Michael Holzheu authored
Since commit d86bd1be ("mm/slub: support left redzone") it is no longer guaranteed that kmalloc(PAGE_SIZE) returns page aligned memory. After the above commit we get an error for diag224 because aligned memory is required. This leads to the following user visible error: # mount none -t s390_hypfs /sys/hypervisor/ mount: unknown filesystem type 's390_hypfs' # dmesg | grep hypfs hypfs.cccfb8: The hardware system does not provide all functions required by hypfs hypfs.7a79f0: Initialization of hypfs failed with rc=-61 Fix this problem and use get_free_page() instead of kmalloc() to get correctly aligned memory. Cc: stable@vger.kernel.org # v3.6+ Signed-off-by: Michael Holzheu <holzheu@linux.vnet.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
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Linus Torvalds authored
Merge misc fixes from Andrew Morton: "20 fixes" * emailed patches from Andrew Morton <akpm@linux-foundation.org>: drivers/misc/sgi-gru/grumain.c: remove bogus 0x prefix from printk cris/arch-v32: cryptocop: print a hex number after a 0x prefix ipack: print a hex number after a 0x prefix block: DAC960: print a hex number after a 0x prefix fs: exofs: print a hex number after a 0x prefix lib/genalloc.c: start search from start of chunk mm: memcontrol: do not recurse in direct reclaim CREDITS: update credit information for Martin Kepplinger proc: fix NULL dereference when reading /proc/<pid>/auxv mm: kmemleak: ensure that the task stack is not freed during scanning lib/stackdepot.c: bump stackdepot capacity from 16MB to 128MB latent_entropy: raise CONFIG_FRAME_WARN by default kconfig.h: remove config_enabled() macro ipc: account for kmem usage on mqueue and msg mm/slab: improve performance of gathering slabinfo stats mm: page_alloc: use KERN_CONT where appropriate mm/list_lru.c: avoid error-path NULL pointer deref h8300: fix syscall restarting kcov: properly check if we are in an interrupt mm/slab: fix kmemcg cache creation delayed issue
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Dimitri Sivanich authored
Would like to have this be a decimal number. Link: http://lkml.kernel.org/r/20161026134746.GA30169@sgi.comSigned-off-by: Dimitri Sivanich <sivanich@sgi.com> Reported-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Uwe Kleine-König authored
It makes the result hard to interpret correctly if a base 10 number is prefixed by 0x. So change to a hex number. Link: http://lkml.kernel.org/r/20161026125658.25728-6-u.kleine-koenig@pengutronix.deSigned-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de> Cc: Mikael Starvik <starvik@axis.com> Cc: Jesper Nilsson <jesper.nilsson@axis.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Uwe Kleine-König authored
It makes the result hard to interpret correctly if a base 10 number is prefixed by 0x. So change to a hex number. Link: http://lkml.kernel.org/r/20161026125658.25728-4-u.kleine-koenig@pengutronix.deSigned-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de> Cc: Samuel Iglesias Gonsalvez <siglesias@igalia.com> Cc: Jens Taprogge <jens.taprogge@taprogge.org> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Uwe Kleine-König authored
It makes the message hard to interpret correctly if a base 10 number is prefixed by 0x. So change to a hex number. Link: http://lkml.kernel.org/r/20161026125658.25728-3-u.kleine-koenig@pengutronix.deSigned-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Uwe Kleine-König authored
It makes the message hard to interpret correctly if a base 10 number is prefixed by 0x. So change to a hex number. Link: http://lkml.kernel.org/r/20161026125658.25728-2-u.kleine-koenig@pengutronix.deSigned-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de> Cc: Boaz Harrosh <ooo@electrozaur.com> Cc: Benny Halevy <bhalevy@primarydata.com> Cc: Joe Perches <joe@perches.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Daniel Mentz authored
gen_pool_alloc_algo() iterates over the chunks of a pool trying to find a contiguous block of memory that satisfies the allocation request. The shortcut if (size > atomic_read(&chunk->avail)) continue; makes the loop skip over chunks that do not have enough bytes left to fulfill the request. There are two situations, though, where an allocation might still fail: (1) The available memory is not contiguous, i.e. the request cannot be fulfilled due to external fragmentation. (2) A race condition. Another thread runs the same code concurrently and is quicker to grab the available memory. In those situations, the loop calls pool->algo() to search the entire chunk, and pool->algo() returns some value that is >= end_bit to indicate that the search failed. This return value is then assigned to start_bit. The variables start_bit and end_bit describe the range that should be searched, and this range should be reset for every chunk that is searched. Today, the code fails to reset start_bit to 0. As a result, prefixes of subsequent chunks are ignored. Memory allocations might fail even though there is plenty of room left in these prefixes of those other chunks. Fixes: 7f184275 ("lib, Make gen_pool memory allocator lockless") Link: http://lkml.kernel.org/r/1477420604-28918-1-git-send-email-danielmentz@google.comSigned-off-by: Daniel Mentz <danielmentz@google.com> Reviewed-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Acked-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Johannes Weiner authored
On 4.0, we saw a stack corruption from a page fault entering direct memory cgroup reclaim, calling into btrfs_releasepage(), which then tried to allocate an extent and recursed back into a kmem charge ad nauseam: [...] btrfs_releasepage+0x2c/0x30 try_to_release_page+0x32/0x50 shrink_page_list+0x6da/0x7a0 shrink_inactive_list+0x1e5/0x510 shrink_lruvec+0x605/0x7f0 shrink_zone+0xee/0x320 do_try_to_free_pages+0x174/0x440 try_to_free_mem_cgroup_pages+0xa7/0x130 try_charge+0x17b/0x830 memcg_charge_kmem+0x40/0x80 new_slab+0x2d9/0x5a0 __slab_alloc+0x2fd/0x44f kmem_cache_alloc+0x193/0x1e0 alloc_extent_state+0x21/0xc0 __clear_extent_bit+0x2b5/0x400 try_release_extent_mapping+0x1a3/0x220 __btrfs_releasepage+0x31/0x70 btrfs_releasepage+0x2c/0x30 try_to_release_page+0x32/0x50 shrink_page_list+0x6da/0x7a0 shrink_inactive_list+0x1e5/0x510 shrink_lruvec+0x605/0x7f0 shrink_zone+0xee/0x320 do_try_to_free_pages+0x174/0x440 try_to_free_mem_cgroup_pages+0xa7/0x130 try_charge+0x17b/0x830 mem_cgroup_try_charge+0x65/0x1c0 handle_mm_fault+0x117f/0x1510 __do_page_fault+0x177/0x420 do_page_fault+0xc/0x10 page_fault+0x22/0x30 On later kernels, kmem charging is opt-in rather than opt-out, and that particular kmem allocation in btrfs_releasepage() is no longer being charged and won't recurse and overrun the stack anymore. But it's not impossible for an accounted allocation to happen from the memcg direct reclaim context, and we needed to reproduce this crash many times before we even got a useful stack trace out of it. Like other direct reclaimers, mark tasks in memcg reclaim PF_MEMALLOC to avoid recursing into any other form of direct reclaim. Then let recursive charges from PF_MEMALLOC contexts bypass the cgroup limit. Link: http://lkml.kernel.org/r/20161025141050.GA13019@cmpxchg.orgSigned-off-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Vladimir Davydov <vdavydov.dev@gmail.com> Cc: Tejun Heo <tj@kernel.org> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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