kernel/git/next/linux-next.git/init/main.c, branch akpm-base

Merge branch 'mm-nonmm-unstable' into mm-everything

2022-06-27T20:45:54+00:00

init/main.c: silence some -Wunused-parameter warnings

2022-06-27T20:45:49+00:00

There are a bunch of callbacks with unused arguments, go ahead and silence those so "make KCFLAGS=-W init/main.o" is a little quieter. Here's a little sample: init/main.c:182:43: warning: unused parameter 'str' [-Wunused-parameter] static int __init set_reset_devices(char *str) Link: https://lkml.kernel.org/r/20210519162341.1275452-1-ahalaney@redhat.com Signed-off-by: Andrew Halaney Cc: Rasmus Villemoes Signed-off-by: Andrew Morton

Maple Tree: add new data structure

2022-06-27T20:44:59+00:00

Patch series "Introducing the Maple Tree". The maple tree is an RCU-safe range based B-tree designed to use modern processor cache efficiently. There are a number of places in the kernel that a non-overlapping range-based tree would be beneficial, especially one with a simple interface. If you use an rbtree with other data structures to improve performance or an interval tree to track non-overlapping ranges, then this is for you. The tree has a branching factor of 10 for non-leaf nodes and 16 for leaf nodes. With the increased branching factor, it is significantly shorter than the rbtree so it has fewer cache misses. The removal of the linked list between subsequent entries also reduces the cache misses and the need to pull in the previous and next VMA during many tree alterations. The first user that is covered in this patch set is the vm_area_struct, where three data structures are replaced by the maple tree: the augmented rbtree, the vma cache, and the linked list of VMAs in the mm_struct. The long term goal is to reduce or remove the mmap_lock contention. The plan is to get to the point where we use the maple tree in RCU mode. Readers will not block for writers. A single write operation will be allowed at a time. A reader re-walks if stale data is encountered. VMAs would be RCU enabled and this mode would be entered once multiple tasks are using the mm_struct. Davidlor said : Yes I like the maple tree, and at this stage I don't think we can ask for : more from this series wrt the MM - albeit there seems to still be some : folks reporting breakage. Fundamentally I see Liam's work to (re)move : complexity out of the MM (not to say that the actual maple tree is not : complex) by consolidating the three complimentary data structures very : much worth it considering performance does not take a hit. This was very : much a turn off with the range locking approach, which worst case scenario : incurred in prohibitive overhead. Also as Liam and Matthew have : mentioned, RCU opens up a lot of nice performance opportunities, and in : addition academia[1] has shown outstanding scalability of address spaces : with the foundation of replacing the locked rbtree with RCU aware trees. A similar work has been discovered in the academic press https://pdos.csail.mit.edu/papers/rcuvm:asplos12.pdf Sheer coincidence. We designed our tree with the intention of solving the hardest problem first. Upon settling on a b-tree variant and a rough outline, we researched ranged based b-trees and RCU b-trees and did find that article. So it was nice to find reassurances that we were on the right path, but our design choice of using ranges made that paper unusable for us. This patch (of 69): The maple tree is an RCU-safe range based B-tree designed to use modern processor cache efficiently. There are a number of places in the kernel that a non-overlapping range-based tree would be beneficial, especially one with a simple interface. If you use an rbtree with other data structures to improve performance or an interval tree to track non-overlapping ranges, then this is for you. The tree has a branching factor of 10 for non-leaf nodes and 16 for leaf nodes. With the increased branching factor, it is significantly shorter than the rbtree so it has fewer cache misses. The removal of the linked list between subsequent entries also reduces the cache misses and the need to pull in the previous and next VMA during many tree alterations. The first user that is covered in this patch set is the vm_area_struct, where three data structures are replaced by the maple tree: the augmented rbtree, the vma cache, and the linked list of VMAs in the mm_struct. The long term goal is to reduce or remove the mmap_lock contention. The plan is to get to the point where we use the maple tree in RCU mode. Readers will not block for writers. A single write operation will be allowed at a time. A reader re-walks if stale data is encountered. VMAs would be RCU enabled and this mode would be entered once multiple tasks are using the mm_struct. Link: https://lkml.kernel.org/r/20220621204632.3370049-1-Liam.Howlett@oracle.com Link: https://lkml.kernel.org/r/20220504010716.661115-1-Liam.Howlett@oracle.com Link: https://lkml.kernel.org/r/20220504002554.654642-1-Liam.Howlett@oracle.com Link: https://lkml.kernel.org/r/20220504010716.661115-3-Liam.Howlett@oracle.com Link: https://lkml.kernel.org/r/20220511144304.1430851-2-Liam.Howlett@oracle.com Link: https://lkml.kernel.org/r/20220517145913.3480729-1-Liam.Howlett@oracle.com Link: https://lkml.kernel.org/r/20220517152209.3486724-1-Liam.Howlett@oracle.com Link: https://lkml.kernel.org/r/20220519150304.1289636-1-Liam.Howlett@oracle.com Link: https://lkml.kernel.org/r/20220607063834.7004-1-lukas.bulwahn@gmail.com Link: https://lkml.kernel.org/r/20220615141921.417598-2-Liam.Howlett@oracle.com Link: https://lkml.kernel.org/r/20220615141921.417598-3-Liam.Howlett@oracle.com Link: https://lkml.kernel.org/r/20220616011739.802669-3-Liam.Howlett@oracle.com Link: https://lkml.kernel.org/r/20220615174213.738849-1-Liam.Howlett@oracle.com Link: https://lkml.kernel.org/r/20220617134609.1771611-1-Liam.Howlett@oracle.com Link: https://lkml.kernel.org/r/20220621204632.3370049-2-Liam.Howlett@oracle.com Signed-off-by: Liam R. Howlett Signed-off-by: Matthew Wilcox (Oracle) Tested-by: David Howells Tested-by: Sven Schnelle Signed-off-by: Lukas Bulwahn Cc: Catalin Marinas Cc: SeongJae Park Cc: Vlastimil Babka Cc: Will Deacon Cc: Davidlohr Bueso Signed-off-by: Andrew Morton

Merge tag 'kthread-cleanups-for-v5.19' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace

2022-06-03T23:03:05+00:00

Pull kthread updates from Eric Biederman: "This updates init and user mode helper tasks to be ordinary user mode tasks. Commit 40966e316f86 ("kthread: Ensure struct kthread is present for all kthreads") caused init and the user mode helper threads that call kernel_execve to have struct kthread allocated for them. This struct kthread going away during execve in turned made a use after free of struct kthread possible. Here, commit 343f4c49f243 ("kthread: Don't allocate kthread_struct for init and umh") is enough to fix the use after free and is simple enough to be backportable. The rest of the changes pass struct kernel_clone_args to clean things up and cause the code to make sense. In making init and the user mode helpers tasks purely user mode tasks I ran into two complications. The function task_tick_numa was detecting tasks without an mm by testing for the presence of PF_KTHREAD. The initramfs code in populate_initrd_image was using flush_delayed_fput to ensuere the closing of all it's file descriptors was complete, and flush_delayed_fput does not work in a userspace thread. I have looked and looked and more complications and in my code review I have not found any, and neither has anyone else with the code sitting in linux-next" * tag 'kthread-cleanups-for-v5.19' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace: sched: Update task_tick_numa to ignore tasks without an mm fork: Stop allowing kthreads to call execve fork: Explicitly set PF_KTHREAD init: Deal with the init process being a user mode process fork: Generalize PF_IO_WORKER handling fork: Explicity test for idle tasks in copy_thread fork: Pass struct kernel_clone_args into copy_thread kthread: Don't allocate kthread_struct for init and umh

Merge tag 'trace-v5.19' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace

2022-05-29T17:31:36+00:00

Pull tracing updates from Steven Rostedt: "The majority of the changes are for fixes and clean ups. Notable changes: - Rework trace event triggers code to be easier to interact with. - Support for embedding bootconfig with the kernel (as suppose to having it embedded in initram). This is useful for embedded boards without initram disks. - Speed up boot by parallelizing the creation of tracefs files. - Allow absolute ring buffer timestamps handle timestamps that use more than 59 bits. - Added new tracing clock "TAI" (International Atomic Time) - Have weak functions show up in available_filter_function list as: __ftrace_invalid_address___ instead of using the name of the function before it" * tag 'trace-v5.19' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace: (52 commits) ftrace: Add FTRACE_MCOUNT_MAX_OFFSET to avoid adding weak function tracing: Fix comments for event_trigger_separate_filter() x86/traceponit: Fix comment about irq vector tracepoints x86,tracing: Remove unused headers ftrace: Clean up hash direct_functions on register failures tracing: Fix comments of create_filter() tracing: Disable kcov on trace_preemptirq.c tracing: Initialize integer variable to prevent garbage return value ftrace: Fix typo in comment ftrace: Remove return value of ftrace_arch_modify_*() tracing: Cleanup code by removing init "char *name" tracing: Change "char *" string form to "char []" tracing/timerlat: Do not wakeup the thread if the trace stops at the IRQ tracing/timerlat: Print stacktrace in the IRQ handler if needed tracing/timerlat: Notify IRQ new max latency only if stop tracing is set kprobes: Fix build errors with CONFIG_KRETPROBES=n tracing: Fix return value of trace_pid_write() tracing: Fix potential double free in create_var_ref() tracing: Use strim() to remove whitespace instead of doing it manually ftrace: Deal with error return code of the ftrace_process_locs() function ...

random: handle latent entropy and command line from random_init()

2022-05-18T13:53:53+00:00

Currently, start_kernel() adds latent entropy and the command line to the entropy bool *after* the RNG has been initialized, deferring when it's actually used by things like stack canaries until the next time the pool is seeded. This surely is not intended. Rather than splitting up which entropy gets added where and when between start_kernel() and random_init(), just do everything in random_init(), which should eliminate these kinds of bugs in the future. While we're at it, rename the awkwardly titled "rand_initialize()" to the more standard "random_init()" nomenclature. Reviewed-by: Dominik Brodowski Signed-off-by: Jason A. Donenfeld

init: call time_init() before rand_initialize()

2022-05-13T21:59:22+00:00

Currently time_init() is called after rand_initialize(), but rand_initialize() makes use of the timer on various platforms, and sometimes this timer needs to be initialized by time_init() first. In order for random_get_entropy() to not return zero during early boot when it's potentially used as an entropy source, reverse the order of these two calls. The block doing random initialization was right before time_init() before, so changing the order shouldn't have any complicated effects. Cc: Andrew Morton Reviewed-by: Stafford Horne Signed-off-by: Jason A. Donenfeld

kthread: Don't allocate kthread_struct for init and umh

2022-05-06T19:49:44+00:00

If kthread_is_per_cpu runs concurrently with free_kthread_struct the kthread_struct that was just freed may be read from. This bug was introduced by commit 40966e316f86 ("kthread: Ensure struct kthread is present for all kthreads"). When kthread_struct started to be allocated for all tasks that have PF_KTHREAD set. This in turn required the kthread_struct to be freed in kernel_execve and violated the assumption that kthread_struct will have the same lifetime as the task. Looking a bit deeper this only applies to callers of kernel_execve which is just the init process and the user mode helper processes. These processes really don't want to be kernel threads but are for historical reasons. Mostly that copy_thread does not know how to take a kernel mode function to the process with for processes without PF_KTHREAD or PF_IO_WORKER set. Solve this by not allocating kthread_struct for the init process and the user mode helper processes. This is done by adding a kthread member to struct kernel_clone_args. Setting kthread in fork_idle and kernel_thread. Adding user_mode_thread that works like kernel_thread except it does not set kthread. In fork only allocating the kthread_struct if .kthread is set. I have looked at kernel/kthread.c and since commit 40966e316f86 ("kthread: Ensure struct kthread is present for all kthreads") there have been no assumptions added that to_kthread or __to_kthread will not return NULL. There are a few callers of to_kthread or __to_kthread that assume a non-NULL struct kthread pointer will be returned. These functions are kthread_data(), kthread_parmme(), kthread_exit(), kthread(), kthread_park(), kthread_unpark(), kthread_stop(). All of those functions can reasonably expected to be called when it is know that a task is a kthread so that assumption seems reasonable. Cc: stable@vger.kernel.org Fixes: 40966e316f86 ("kthread: Ensure struct kthread is present for all kthreads") Reported-by: Максим Кутявин Link: https://lkml.kernel.org/r/20220506141512.516114-1-ebiederm@xmission.com Signed-off-by: "Eric W. Biederman"

bootconfig: Support embedding a bootconfig file in kernel

2022-04-26T21:58:51+00:00

This allows kernel developer to embed a default bootconfig file in the kernel instead of embedding it in the initrd. This will be good for who are using the kernel without initrd, or who needs a default bootconfigs. This needs to set two kconfigs: CONFIG_BOOT_CONFIG_EMBED=y and set the file path to CONFIG_BOOT_CONFIG_EMBED_FILE. Note that you still need 'bootconfig' command line option to load the embedded bootconfig. Also if you boot using an initrd with a different bootconfig, the kernel will use the bootconfig in the initrd, instead of the default bootconfig. Link: https://lkml.kernel.org/r/164921227943.1090670.14035119557571329218.stgit@devnote2 Cc: Padmanabha Srinivasaiah Cc: Jonathan Corbet Cc: Randy Dunlap Cc: Nick Desaulniers Cc: Sami Tolvanen Cc: Nathan Chancellor Cc: Masahiro Yamada Cc: Linux Kbuild mailing list Signed-off-by: Masami Hiramatsu Signed-off-by: Steven Rostedt (Google)

bootconfig: Check the checksum before removing the bootconfig from initrd

2022-04-26T21:58:51+00:00

Check the bootconfig's checksum before removing the bootconfig data from initrd to avoid modifying initrd by mistake. This will also simplifies the get_boot_config_from_initrd() interface. Link: https://lkml.kernel.org/r/164921226891.1090670.16955839243639298134.stgit@devnote2 Cc: Padmanabha Srinivasaiah Cc: Jonathan Corbet Cc: Randy Dunlap Cc: Nick Desaulniers Cc: Sami Tolvanen Cc: Nathan Chancellor Cc: Masahiro Yamada Cc: Linux Kbuild mailing list Signed-off-by: Masami Hiramatsu Signed-off-by: Steven Rostedt (Google)