kernel.git/drivers/s390/char, branch linux-4.20.y

s390/smp: fix CPU hotplug deadlock with CPU rescan

2019-01-31T07:15:38Z

commit b7cb707c373094ce4008d4a6ac9b6b366ec52da5 upstream. smp_rescan_cpus() is called without the device_hotplug_lock, which can lead to a dedlock when a new CPU is found and immediately set online by a udev rule. This was observed on an older kernel version, where the cpu_hotplug_begin() loop was still present, and it resulted in hanging chcpu and systemd-udev processes. This specific deadlock will not show on current kernels. However, there may be other possible deadlocks, and since smp_rescan_cpus() can still trigger a CPU hotplug operation, the device_hotplug_lock should be held. For reference, this was the deadlock with the old cpu_hotplug_begin() loop: chcpu (rescan) systemd-udevd echo 1 > /sys/../rescan -> smp_rescan_cpus() -> (*) get_online_cpus() (increases refcount) -> smp_add_present_cpu() (new CPU found) -> register_cpu() -> device_add() -> udev "add" event triggered -----------> udev rule sets CPU online -> echo 1 > /sys/.../online -> lock_device_hotplug_sysfs() (this is missing in rescan path) -> device_online() -> (**) device_lock(new CPU dev) -> cpu_up() -> cpu_hotplug_begin() (loops until refcount == 0) -> deadlock with (*) -> bus_probe_device() -> device_attach() -> device_lock(new CPU dev) -> deadlock with (**) Fix this by taking the device_hotplug_lock in the CPU rescan path. Cc: Signed-off-by: Gerald Schaefer Signed-off-by: Martin Schwidefsky Signed-off-by: Greg Kroah-Hartman

mm: remove include/linux/bootmem.h

2018-10-31T15:54:16Z

Move remaining definitions and declarations from include/linux/bootmem.h into include/linux/memblock.h and remove the redundant header. The includes were replaced with the semantic patch below and then semi-automated removal of duplicated '#include @@ @@ - #include + #include [sfr@canb.auug.org.au: dma-direct: fix up for the removal of linux/bootmem.h] Link: http://lkml.kernel.org/r/20181002185342.133d1680@canb.auug.org.au [sfr@canb.auug.org.au: powerpc: fix up for removal of linux/bootmem.h] Link: http://lkml.kernel.org/r/20181005161406.73ef8727@canb.auug.org.au [sfr@canb.auug.org.au: x86/kaslr, ACPI/NUMA: fix for linux/bootmem.h removal] Link: http://lkml.kernel.org/r/20181008190341.5e396491@canb.auug.org.au Link: http://lkml.kernel.org/r/1536927045-23536-30-git-send-email-rppt@linux.vnet.ibm.com Signed-off-by: Mike Rapoport Signed-off-by: Stephen Rothwell Acked-by: Michal Hocko Cc: Catalin Marinas Cc: Chris Zankel Cc: "David S. Miller" Cc: Geert Uytterhoeven Cc: Greentime Hu Cc: Greg Kroah-Hartman Cc: Guan Xuetao Cc: Ingo Molnar Cc: "James E.J. Bottomley" Cc: Jonas Bonn Cc: Jonathan Corbet Cc: Ley Foon Tan Cc: Mark Salter Cc: Martin Schwidefsky Cc: Matt Turner Cc: Michael Ellerman Cc: Michal Simek Cc: Palmer Dabbelt Cc: Paul Burton Cc: Richard Kuo Cc: Richard Weinberger Cc: Rich Felker Cc: Russell King Cc: Serge Semin Cc: Thomas Gleixner Cc: Tony Luck Cc: Vineet Gupta Cc: Yoshinori Sato Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

s390/kasan: avoid instrumentation of early C code

2018-10-09T09:21:17Z

Instrumented C code cannot run without the kasan shadow area. Exempt source code files from kasan which are running before / used during kasan initialization. Reviewed-by: Martin Schwidefsky Signed-off-by: Vasily Gorbik Signed-off-by: Martin Schwidefsky

s390/sclp: introduce sclp_early_get_hsa_size

2018-10-09T09:21:13Z

Introduce sclp_early_get_hsa_size function to be used during early memory detection. This function allows to find a memory limit imposed during zfcpdump. Reviewed-by: Heiko Carstens Reviewed-by: Martin Schwidefsky Signed-off-by: Vasily Gorbik Signed-off-by: Martin Schwidefsky

s390/mem_detect: replace tprot loop with binary search

2018-10-09T09:21:12Z

In a situation when other memory detection methods are not available (no SCLP and no z/VM diag260), continuous online memory is assumed. Replacing tprot loop with faster binary search, as only online memory end has to be found. Reviewed-by: Heiko Carstens Reviewed-by: Martin Schwidefsky Signed-off-by: Vasily Gorbik Signed-off-by: Martin Schwidefsky

s390/mem_detect: introduce SCLP storage info

2018-10-09T09:21:09Z

SCLP storage info allows to detect continuous and non-continuous online memory under LPAR, z/VM and KVM, when standby memory is defined. Reviewed-by: Heiko Carstens Reviewed-by: Martin Schwidefsky Signed-off-by: Vasily Gorbik Signed-off-by: Martin Schwidefsky

s390/mem_detect: move tprot loop to early boot phase

2018-10-09T09:21:08Z

Move memory detection to early boot phase. To store online memory regions "struct mem_detect_info" has been introduced together with for_each_mem_detect_block iterator. mem_detect_info is later converted to memblock. Also introduces sclp_early_get_meminfo function to get maximum physical memory and maximum increment number. Reviewed-by: Heiko Carstens Reviewed-by: Martin Schwidefsky Signed-off-by: Vasily Gorbik Signed-off-by: Martin Schwidefsky

s390/sclp: move sclp_early_read_info to sclp_early_core.c

2018-10-09T09:21:07Z

To enable early online memory detection sclp_early_read_info has been moved to sclp_early_core.c. sclp_info_sccb has been made a part of .boot.data, which allows to reuse it later during early kernel startup and make sclp_early_read_info call just once. Reviewed-by: Heiko Carstens Reviewed-by: Martin Schwidefsky Signed-off-by: Vasily Gorbik Signed-off-by: Martin Schwidefsky

s390/sclp: simplify early hsa_size detection

2018-10-09T09:21:04Z

Architecture documentation suggests that hsa_size has been available in the read info since the list-directed ipl dump has been introduced. By using this value few early sclp calls could be avoided. Reviewed-by: Heiko Carstens Reviewed-by: Martin Schwidefsky Signed-off-by: Vasily Gorbik Signed-off-by: Martin Schwidefsky

s390/monwriter: do not use stack buffers for hardware data

2018-10-09T09:20:53Z

With CONFIG_VMAP_STACK=y the stack is allocated from the vmalloc space. Data structures passed to a hardware or a hypervisor interface that requires V=R can not be allocated on the stack anymore. Use kmalloc to get memory for the appldata_parameter_list and appldata_product_id structures. Reviewed-by: Gerald Schaefer Signed-off-by: Martin Schwidefsky