user/sven/linux.git/kernel/notifier.c, branch v5.12-rc2

notifier: Fix broken error handling pattern

2020-09-01T07:58:03Z

The current notifiers have the following error handling pattern all over the place: int err, nr; err = __foo_notifier_call_chain(&chain, val_up, v, -1, &nr); if (err & NOTIFIER_STOP_MASK) __foo_notifier_call_chain(&chain, val_down, v, nr-1, NULL) And aside from the endless repetition thereof, it is broken. Consider blocking notifiers; both calls take and drop the rwsem, this means that the notifier list can change in between the two calls, making @nr meaningless. Fix this by replacing all the __foo_notifier_call_chain() functions with foo_notifier_call_chain_robust() that embeds the above pattern, but ensures it is inside a single lock region. Note: I switched atomic_notifier_call_chain_robust() to use the spinlock, since RCU cannot provide the guarantee required for the recovery. Note: software_resume() error handling was broken afaict. Signed-off-by: Peter Zijlstra (Intel) Signed-off-by: Ingo Molnar Acked-by: Rafael J. Wysocki Link: https://lore.kernel.org/r/20200818135804.325626653@infradead.org

mm: remove vmalloc_sync_(un)mappings()

2020-06-02T17:59:12Z

These functions are not needed anymore because the vmalloc and ioremap mappings are now synchronized when they are created or torn down. Remove all callers and function definitions. Signed-off-by: Joerg Roedel Signed-off-by: Andrew Morton Tested-by: Steven Rostedt (VMware) Acked-by: Andy Lutomirski Acked-by: Peter Zijlstra (Intel) Cc: Arnd Bergmann Cc: Christoph Hellwig Cc: Dave Hansen Cc: "H . Peter Anvin" Cc: Ingo Molnar Cc: Matthew Wilcox (Oracle) Cc: Michal Hocko Cc: "Rafael J. Wysocki" Cc: Thomas Gleixner Cc: Vlastimil Babka Link: http://lkml.kernel.org/r/20200515140023.25469-7-joro@8bytes.org Signed-off-by: Linus Torvalds

x86/mm: split vmalloc_sync_all()

2020-03-22T01:56:06Z

Commit 3f8fd02b1bf1 ("mm/vmalloc: Sync unmappings in __purge_vmap_area_lazy()") introduced a call to vmalloc_sync_all() in the vunmap() code-path. While this change was necessary to maintain correctness on x86-32-pae kernels, it also adds additional cycles for architectures that don't need it. Specifically on x86-64 with CONFIG_VMAP_STACK=y some people reported severe performance regressions in micro-benchmarks because it now also calls the x86-64 implementation of vmalloc_sync_all() on vunmap(). But the vmalloc_sync_all() implementation on x86-64 is only needed for newly created mappings. To avoid the unnecessary work on x86-64 and to gain the performance back, split up vmalloc_sync_all() into two functions: * vmalloc_sync_mappings(), and * vmalloc_sync_unmappings() Most call-sites to vmalloc_sync_all() only care about new mappings being synchronized. The only exception is the new call-site added in the above mentioned commit. Shile Zhang directed us to a report of an 80% regression in reaim throughput. Fixes: 3f8fd02b1bf1 ("mm/vmalloc: Sync unmappings in __purge_vmap_area_lazy()") Reported-by: kernel test robot Reported-by: Shile Zhang Signed-off-by: Joerg Roedel Signed-off-by: Andrew Morton Tested-by: Borislav Petkov Acked-by: Rafael J. Wysocki [GHES] Cc: Dave Hansen Cc: Andy Lutomirski Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: Ingo Molnar Cc: Link: http://lkml.kernel.org/r/20191009124418.8286-1-joro@8bytes.org Link: https://lists.01.org/hyperkitty/list/lkp@lists.01.org/thread/4D3JPPHBNOSPFK2KEPC6KGKS6J25AIDB/ Link: http://lkml.kernel.org/r/20191113095530.228959-1-shile.zhang@linux.alibaba.com Signed-off-by: Linus Torvalds

kernel/notifier.c: remove blocking_notifier_chain_cond_register()

2019-12-05T03:44:12Z

blocking_notifier_chain_cond_register() does not consider system_booting state, which is the only difference between this function and blocking_notifier_cain_register(). This can be a bug and is a piece of duplicate code. Delete blocking_notifier_chain_cond_register() Link: http://lkml.kernel.org/r/1568861888-34045-4-git-send-email-nixiaoming@huawei.com Signed-off-by: Xiaoming Ni Reviewed-by: Andrew Morton Cc: Alan Stern Cc: Alexey Dobriyan Cc: Andy Lutomirski Cc: Anna Schumaker Cc: Arjan van de Ven Cc: Chuck Lever Cc: David S. Miller Cc: Ingo Molnar Cc: J. Bruce Fields Cc: Jeff Layton Cc: Nadia Derbey Cc: "Paul E. McKenney" Cc: Sam Protsenko Cc: Thomas Gleixner Cc: Trond Myklebust Cc: Vasily Averin Cc: Viresh Kumar Cc: YueHaibing Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

kernel/notifier.c: remove notifier_chain_cond_register()

2019-12-05T03:44:12Z

The only difference between notifier_chain_cond_register() and notifier_chain_register() is the lack of warning hints for duplicate registrations. Use notifier_chain_register() instead of notifier_chain_cond_register() to avoid duplicate code Link: http://lkml.kernel.org/r/1568861888-34045-3-git-send-email-nixiaoming@huawei.com Signed-off-by: Xiaoming Ni Reviewed-by: Andrew Morton Cc: Alan Stern Cc: Alexey Dobriyan Cc: Andy Lutomirski Cc: Anna Schumaker Cc: Arjan van de Ven Cc: Chuck Lever Cc: David S. Miller Cc: Ingo Molnar Cc: J. Bruce Fields Cc: Jeff Layton Cc: Nadia Derbey Cc: "Paul E. McKenney" Cc: Sam Protsenko Cc: Thomas Gleixner Cc: Trond Myklebust Cc: Vasily Averin Cc: Viresh Kumar Cc: YueHaibing Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

kernel/notifier.c: intercept duplicate registrations to avoid infinite loops

2019-12-05T03:44:12Z

Registering the same notifier to a hook repeatedly can cause the hook list to form a ring or lose other members of the list. case1: An infinite loop in notifier_chain_register() can cause soft lockup atomic_notifier_chain_register(&test_notifier_list, &test1); atomic_notifier_chain_register(&test_notifier_list, &test1); atomic_notifier_chain_register(&test_notifier_list, &test2); case2: An infinite loop in notifier_chain_register() can cause soft lockup atomic_notifier_chain_register(&test_notifier_list, &test1); atomic_notifier_chain_register(&test_notifier_list, &test1); atomic_notifier_call_chain(&test_notifier_list, 0, NULL); case3: lose other hook test2 atomic_notifier_chain_register(&test_notifier_list, &test1); atomic_notifier_chain_register(&test_notifier_list, &test2); atomic_notifier_chain_register(&test_notifier_list, &test1); case4: Unregister returns 0, but the hook is still in the linked list, and it is not really registered. If you call notifier_call_chain after ko is unloaded, it will trigger oops. If the system is configured with softlockup_panic and the same hook is repeatedly registered on the panic_notifier_list, it will cause a loop panic. Add a check in notifier_chain_register(), intercepting duplicate registrations to avoid infinite loops Link: http://lkml.kernel.org/r/1568861888-34045-2-git-send-email-nixiaoming@huawei.com Signed-off-by: Xiaoming Ni Reviewed-by: Vasily Averin Reviewed-by: Andrew Morton Cc: Alexey Dobriyan Cc: Anna Schumaker Cc: Arjan van de Ven Cc: J. Bruce Fields Cc: Chuck Lever Cc: David S. Miller Cc: Jeff Layton Cc: Andy Lutomirski Cc: Ingo Molnar Cc: Nadia Derbey Cc: "Paul E. McKenney" Cc: Sam Protsenko Cc: Alan Stern Cc: Thomas Gleixner Cc: Trond Myklebust Cc: Viresh Kumar Cc: Xiaoming Ni Cc: YueHaibing Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

treewide: Add SPDX license identifier for missed files

2019-05-21T08:50:45Z

Add SPDX license identifiers to all files which: - Have no license information of any form - Have EXPORT_.*_SYMBOL_GPL inside which was used in the initial scan/conversion to ignore the file These files fall under the project license, GPL v2 only. The resulting SPDX license identifier is: GPL-2.0-only Signed-off-by: Thomas Gleixner Signed-off-by: Greg Kroah-Hartman

kernel/notifier.c: double register detection

2019-05-15T02:52:49Z

By design notifiers can be registerd once only, 2nd register attempt called by mistake silently corrupts notifiers list. A few years ago I investigated described problem, the host was power cycled because of notifier list corruption. I've prepared this patch and applied it to the OpenVZ kernel and sent this patch but nobody commented on it. Later it helped us to detect a similar problem in the OpenVz kernel. Mistakes with notifier registration can happen for example during subsystem initialization from different namespaces, or because of a lost unregister in the roll-back path on initialization failures. The proposed check cannot prevent the described problem, however it allows us to detect its reason quickly without coredump analysis. Link: http://lkml.kernel.org/r/04127e71-4782-9bbb-fe5a-7c01e93a99b0@virtuozzo.com Signed-off-by: Vasily Averin Reviewed-by: Andrew Morton Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

kernel/notifier.c: simplify expression

2017-02-25T01:46:56Z

NOTIFY_STOP_MASK (0x8000) has only one bit set and there is no need to compare output of "ret & NOTIFY_STOP_MASK" to NOTIFY_STOP_MASK. We just need to make sure the output is non-zero, that's it. Link: http://lkml.kernel.org/r/88ee58264a2bfab1c97ffc8ac753e25f55f57c10.1483593065.git.viresh.kumar@linaro.org Signed-off-by: Viresh Kumar Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

Merge branch 'x86-asm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2015-09-01T15:40:25Z

Pull x86 asm changes from Ingo Molnar: "The biggest changes in this cycle were: - Revamp, simplify (and in some cases fix) Time Stamp Counter (TSC) primitives. (Andy Lutomirski) - Add new, comprehensible entry and exit handlers written in C. (Andy Lutomirski) - vm86 mode cleanups and fixes. (Brian Gerst) - 32-bit compat code cleanups. (Brian Gerst) The amount of simplification in low level assembly code is already palpable: arch/x86/entry/entry_32.S | 130 +---- arch/x86/entry/entry_64.S | 197 ++----- but more simplifications are planned. There's also the usual laudry mix of low level changes - see the changelog for details" * 'x86-asm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (83 commits) x86/asm: Drop repeated macro of X86_EFLAGS_AC definition x86/asm/msr: Make wrmsrl() a function x86/asm/delay: Introduce an MWAITX-based delay with a configurable timer x86/asm: Add MONITORX/MWAITX instruction support x86/traps: Weaken context tracking entry assertions x86/asm/tsc: Add rdtscll() merge helper selftests/x86: Add syscall_nt selftest selftests/x86: Disable sigreturn_64 x86/vdso: Emit a GNU hash x86/entry: Remove do_notify_resume(), syscall_trace_leave(), and their TIF masks x86/entry/32: Migrate to C exit path x86/entry/32: Remove 32-bit syscall audit optimizations x86/vm86: Rename vm86->v86flags and v86mask x86/vm86: Rename vm86->vm86_info to user_vm86 x86/vm86: Clean up vm86.h includes x86/vm86: Move the vm86 IRQ definitions to vm86.h x86/vm86: Use the normal pt_regs area for vm86 x86/vm86: Eliminate 'struct kernel_vm86_struct' x86/vm86: Move fields from 'struct kernel_vm86_struct' to 'struct vm86' x86/vm86: Move vm86 fields out of 'thread_struct' ...