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2022-04-20dma-direct: avoid redundant memory sync for swiotlbChao Gao1-1/+2
commit 9e02977bfad006af328add9434c8bffa40e053bb upstream. When we looked into FIO performance with swiotlb enabled in VM, we found swiotlb_bounce() is always called one more time than expected for each DMA read request. It turns out that the bounce buffer is copied to original DMA buffer twice after the completion of a DMA request (one is done by in dma_direct_sync_single_for_cpu(), the other by swiotlb_tbl_unmap_single()). But the content in bounce buffer actually doesn't change between the two rounds of copy. So, one round of copy is redundant. Pass DMA_ATTR_SKIP_CPU_SYNC flag to swiotlb_tbl_unmap_single() to skip the memory copy in it. This fix increases FIO 64KB sequential read throughput in a guest with swiotlb=force by 5.6%. Fixes: 55897af63091 ("dma-direct: merge swiotlb_dma_ops into the dma_direct code") Reported-by: Wang Zhaoyang1 <zhaoyang1.wang@intel.com> Reported-by: Gao Liang <liang.gao@intel.com> Signed-off-by: Chao Gao <chao.gao@intel.com> Reviewed-by: Kevin Tian <kevin.tian@intel.com> Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-04-20timers: Fix warning condition in __run_timers()Anna-Maria Behnsen1-4/+7
commit c54bc0fc84214b203f7a0ebfd1bd308ce2abe920 upstream. When the timer base is empty, base::next_expiry is set to base::clk + NEXT_TIMER_MAX_DELTA and base::next_expiry_recalc is false. When no timer is queued until jiffies reaches base::next_expiry value, the warning for not finding any expired timer and base::next_expiry_recalc is false in __run_timers() triggers. To prevent triggering the warning in this valid scenario base::timers_pending needs to be added to the warning condition. Fixes: 31cd0e119d50 ("timers: Recalculate next timer interrupt only when necessary") Reported-by: Johannes Berg <johannes@sipsolutions.net> Signed-off-by: Anna-Maria Behnsen <anna-maria@linutronix.de> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Frederic Weisbecker <frederic@kernel.org> Link: https://lore.kernel.org/r/20220405191732.7438-3-anna-maria@linutronix.de Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-04-20smp: Fix offline cpu check in flush_smp_call_function_queue()Nadav Amit1-1/+1
commit 9e949a3886356fe9112c6f6f34a6e23d1d35407f upstream. The check in flush_smp_call_function_queue() for callbacks that are sent to offline CPUs currently checks whether the queue is empty. However, flush_smp_call_function_queue() has just deleted all the callbacks from the queue and moved all the entries into a local list. This checks would only be positive if some callbacks were added in the short time after llist_del_all() was called. This does not seem to be the intention of this check. Change the check to look at the local list to which the entries were moved instead of the queue from which all the callbacks were just removed. Fixes: 8d056c48e4862 ("CPU hotplug, smp: flush any pending IPI callbacks before CPU offline") Signed-off-by: Nadav Amit <namit@vmware.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Link: https://lore.kernel.org/r/20220319072015.1495036-1-namit@vmware.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-04-20tick/nohz: Use WARN_ON_ONCE() to prevent console saturationPaul Gortmaker1-1/+1
commit 40e97e42961f8c6cc7bd5fe67cc18417e02d78f1 upstream. While running some testing on code that happened to allow the variable tick_nohz_full_running to get set but with no "possible" NOHZ cores to back up that setting, this warning triggered: if (unlikely(tick_do_timer_cpu == TICK_DO_TIMER_NONE)) WARN_ON(tick_nohz_full_running); The console was overwhemled with an endless stream of one WARN per tick per core and there was no way to even see what was going on w/o using a serial console to capture it and then trace it back to this. Change it to WARN_ON_ONCE(). Fixes: 08ae95f4fd3b ("nohz_full: Allow the boot CPU to be nohz_full") Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: stable@vger.kernel.org Link: https://lore.kernel.org/r/20211206145950.10927-3-paul.gortmaker@windriver.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-04-20genirq/affinity: Consider that CPUs on nodes can be unbalancedRei Yamamoto1-2/+3
commit 08d835dff916bfe8f45acc7b92c7af6c4081c8a7 upstream. If CPUs on a node are offline at boot time, the number of nodes is different when building affinity masks for present cpus and when building affinity masks for possible cpus. This causes the following problem: In the case that the number of vectors is less than the number of nodes there are cases where bits of masks for present cpus are overwritten when building masks for possible cpus. Fix this by excluding CPUs, which are not part of the current build mask (present/possible). [ tglx: Massaged changelog and added comment ] Fixes: b82592199032 ("genirq/affinity: Spread IRQs to all available NUMA nodes") Signed-off-by: Rei Yamamoto <yamamoto.rei@jp.fujitsu.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Ming Lei <ming.lei@redhat.com> Cc: stable@vger.kernel.org Link: https://lore.kernel.org/r/20220331003309.10891-1-yamamoto.rei@jp.fujitsu.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-04-13cgroup: Use open-time credentials for process migraton perm checksTejun Heo2-4/+20
commit 1756d7994ad85c2479af6ae5a9750b92324685af upstream. cgroup process migration permission checks are performed at write time as whether a given operation is allowed or not is dependent on the content of the write - the PID. This currently uses current's credentials which is a potential security weakness as it may allow scenarios where a less privileged process tricks a more privileged one into writing into a fd that it created. This patch makes both cgroup2 and cgroup1 process migration interfaces to use the credentials saved at the time of open (file->f_cred) instead of current's. Reported-by: "Eric W. Biederman" <ebiederm@xmission.com> Suggested-by: Linus Torvalds <torvalds@linuxfoundation.org> Fixes: 187fe84067bd ("cgroup: require write perm on common ancestor when moving processes on the default hierarchy") Reviewed-by: Michal Koutný <mkoutny@suse.com> Signed-off-by: Tejun Heo <tj@kernel.org> [OP: apply original __cgroup_procs_write() changes to cgroup_threads_write() and cgroup_procs_write(), as the refactoring commit da70862efe006 ("cgroup: cgroup.{procs,threads} factor out common parts") is not present in 5.10-stable] Signed-off-by: Ovidiu Panait <ovidiu.panait@windriver.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-04-08bpf: Adjust BPF stack helper functions to accommodate skip > 0Namhyung Kim1-32/+24
commit ee2a098851bfbe8bcdd964c0121f4246f00ff41e upstream. Let's say that the caller has storage for num_elem stack frames. Then, the BPF stack helper functions walk the stack for only num_elem frames. This means that if skip > 0, one keeps only 'num_elem - skip' frames. This is because it sets init_nr in the perf_callchain_entry to the end of the buffer to save num_elem entries only. I believe it was because the perf callchain code unwound the stack frames until it reached the global max size (sysctl_perf_event_max_stack). However it now has perf_callchain_entry_ctx.max_stack to limit the iteration locally. This simplifies the code to handle init_nr in the BPF callstack entries and removes the confusion with the perf_event's __PERF_SAMPLE_CALLCHAIN_EARLY which sets init_nr to 0. Also change the comment on bpf_get_stack() in the header file to be more explicit what the return value means. Fixes: c195651e565a ("bpf: add bpf_get_stack helper") Signed-off-by: Namhyung Kim <namhyung@kernel.org> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Yonghong Song <yhs@fb.com> Link: https://lore.kernel.org/bpf/30a7b5d5-6726-1cc2-eaee-8da2828a9a9c@oracle.com Link: https://lore.kernel.org/bpf/20220314182042.71025-1-namhyung@kernel.org Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Based-on-patch-by: Eugene Loh <eugene.loh@oracle.com>
2022-04-08watch_queue: Free the page array when watch_queue is dismantledEric Dumazet1-0/+1
commit b490207017ba237d97b735b2aa66dc241ccd18f5 upstream. Commit 7ea1a0124b6d ("watch_queue: Free the alloc bitmap when the watch_queue is torn down") took care of the bitmap, but not the page array. BUG: memory leak unreferenced object 0xffff88810d9bc140 (size 32): comm "syz-executor335", pid 3603, jiffies 4294946994 (age 12.840s) hex dump (first 32 bytes): 40 a7 40 04 00 ea ff ff 00 00 00 00 00 00 00 00 @.@............. 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ backtrace: kmalloc_array include/linux/slab.h:621 [inline] kcalloc include/linux/slab.h:652 [inline] watch_queue_set_size+0x12f/0x2e0 kernel/watch_queue.c:251 pipe_ioctl+0x82/0x140 fs/pipe.c:632 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:874 [inline] __se_sys_ioctl fs/ioctl.c:860 [inline] __x64_sys_ioctl+0xfc/0x140 fs/ioctl.c:860 do_syscall_x64 arch/x86/entry/common.c:50 [inline] Reported-by: syzbot+25ea042ae28f3888727a@syzkaller.appspotmail.com Fixes: c73be61cede5 ("pipe: Add general notification queue support") Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David Howells <dhowells@redhat.com> Cc: Jann Horn <jannh@google.com> Link: https://lore.kernel.org/r/20220322004654.618274-1-eric.dumazet@gmail.com/ Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-04-08locking/lockdep: Iterate lock_classes directly when reading lockdep filesWaiman Long3-15/+56
[ Upstream commit fb7275acd6fb988313dddd8d3d19efa70d9015ad ] When dumping lock_classes information via /proc/lockdep, we can't take the lockdep lock as the lock hold time is indeterminate. Iterating over all_lock_classes without holding lock can be dangerous as there is a slight chance that it may branch off to other lists leading to infinite loop or even access invalid memory if changes are made to all_lock_classes list in parallel. To avoid this problem, iteration of lock classes is now done directly on the lock_classes array itself. The lock_classes_in_use bitmap is checked to see if the lock class is being used. To avoid iterating the full array all the times, a new max_lock_class_idx value is added to track the maximum lock_class index that is currently being used. We can theoretically take the lockdep lock for iterating all_lock_classes when other lockdep files (lockdep_stats and lock_stat) are accessed as the lock hold time will be shorter for them. For consistency, they are also modified to iterate the lock_classes array directly. Signed-off-by: Waiman Long <longman@redhat.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/20220211035526.1329503-2-longman@redhat.com Signed-off-by: Sasha Levin <sashal@kernel.org>
2022-04-08kdb: Fix the putarea helper functionDaniel Thompson1-1/+1
[ Upstream commit c1cb81429df462eca1b6ba615cddd21dd3103c46 ] Currently kdb_putarea_size() uses copy_from_kernel_nofault() to write *to* arbitrary kernel memory. This is obviously wrong and means the memory modify ('mm') command is a serious risk to debugger stability: if we poke to a bad address we'll double-fault and lose our debug session. Fix this the (very) obvious way. Note that there are two Fixes: tags because the API was renamed and this patch will only trivially backport as far as the rename (and this is probably enough). Nevertheless Christoph's rename did not introduce this problem so I wanted to record that! Fixes: fe557319aa06 ("maccess: rename probe_kernel_{read,write} to copy_{from,to}_kernel_nofault") Fixes: 5d5314d6795f ("kdb: core for kgdb back end (1 of 2)") Signed-off-by: Daniel Thompson <daniel.thompson@linaro.org> Reviewed-by: Douglas Anderson <dianders@chromium.org> Link: https://lore.kernel.org/r/20220128144055.207267-1-daniel.thompson@linaro.org Signed-off-by: Sasha Levin <sashal@kernel.org>
2022-04-08dma-debug: fix return value of __setup handlersRandy Dunlap1-2/+2
[ Upstream commit 80e4390981618e290616dbd06ea190d4576f219d ] When valid kernel command line parameters dma_debug=off dma_debug_entries=100 are used, they are reported as Unknown parameters and added to init's environment strings, polluting it. Unknown kernel command line parameters "BOOT_IMAGE=/boot/bzImage-517rc5 dma_debug=off dma_debug_entries=100", will be passed to user space. and Run /sbin/init as init process with arguments: /sbin/init with environment: HOME=/ TERM=linux BOOT_IMAGE=/boot/bzImage-517rc5 dma_debug=off dma_debug_entries=100 Return 1 from these __setup handlers to indicate that the command line option has been handled. Fixes: 59d3daafa1726 ("dma-debug: add kernel command line parameters") Signed-off-by: Randy Dunlap <rdunlap@infradead.org> Reported-by: Igor Zhbanov <i.zhbanov@omprussia.ru> Link: lore.kernel.org/r/64644a2f-4a20-bab3-1e15-3b2cdd0defe3@omprussia.ru Cc: Joerg Roedel <joro@8bytes.org> Cc: Christoph Hellwig <hch@lst.de> Cc: Marek Szyprowski <m.szyprowski@samsung.com> Cc: iommu@lists.linux-foundation.org Cc: Robin Murphy <robin.murphy@arm.com> Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Sasha Levin <sashal@kernel.org>
2022-04-08livepatch: Fix build failure on 32 bits processorsChristophe Leroy1-2/+2
[ Upstream commit 2f293651eca3eacaeb56747dede31edace7329d2 ] Trying to build livepatch on powerpc/32 results in: kernel/livepatch/core.c: In function 'klp_resolve_symbols': kernel/livepatch/core.c:221:23: warning: cast to pointer from integer of different size [-Wint-to-pointer-cast] 221 | sym = (Elf64_Sym *)sechdrs[symndx].sh_addr + ELF_R_SYM(relas[i].r_info); | ^ kernel/livepatch/core.c:221:21: error: assignment to 'Elf32_Sym *' {aka 'struct elf32_sym *'} from incompatible pointer type 'Elf64_Sym *' {aka 'struct elf64_sym *'} [-Werror=incompatible-pointer-types] 221 | sym = (Elf64_Sym *)sechdrs[symndx].sh_addr + ELF_R_SYM(relas[i].r_info); | ^ kernel/livepatch/core.c: In function 'klp_apply_section_relocs': kernel/livepatch/core.c:312:35: error: passing argument 1 of 'klp_resolve_symbols' from incompatible pointer type [-Werror=incompatible-pointer-types] 312 | ret = klp_resolve_symbols(sechdrs, strtab, symndx, sec, sec_objname); | ^~~~~~~ | | | Elf32_Shdr * {aka struct elf32_shdr *} kernel/livepatch/core.c:193:44: note: expected 'Elf64_Shdr *' {aka 'struct elf64_shdr *'} but argument is of type 'Elf32_Shdr *' {aka 'struct elf32_shdr *'} 193 | static int klp_resolve_symbols(Elf64_Shdr *sechdrs, const char *strtab, | ~~~~~~~~~~~~^~~~~~~ Fix it by using the right types instead of forcing 64 bits types. Fixes: 7c8e2bdd5f0d ("livepatch: Apply vmlinux-specific KLP relocations early") Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu> Acked-by: Petr Mladek <pmladek@suse.com> Acked-by: Joe Lawrence <joe.lawrence@redhat.com> Acked-by: Miroslav Benes <mbenes@suse.cz> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/5288e11b018a762ea3351cc8fb2d4f15093a4457.1640017960.git.christophe.leroy@csgroup.eu Signed-off-by: Sasha Levin <sashal@kernel.org>
2022-04-08printk: fix return value of printk.devkmsg __setup handlerRandy Dunlap1-2/+4
[ Upstream commit b665eae7a788c5e2bc10f9ac3c0137aa0ad1fc97 ] If an invalid option value is used with "printk.devkmsg=<value>", it is silently ignored. If a valid option value is used, it is honored but the wrong return value (0) is used, indicating that the command line option had an error and was not handled. This string is not added to init's environment strings due to init/main.c::unknown_bootoption() checking for a '.' in the boot option string and then considering that string to be an "Unused module parameter". Print a warning message if a bad option string is used. Always return 1 from the __setup handler to indicate that the command line option has been handled. Fixes: 750afe7babd1 ("printk: add kernel parameter to control writes to /dev/kmsg") Signed-off-by: Randy Dunlap <rdunlap@infradead.org> Reported-by: Igor Zhbanov <i.zhbanov@omprussia.ru> Link: lore.kernel.org/r/64644a2f-4a20-bab3-1e15-3b2cdd0defe3@omprussia.ru Cc: Borislav Petkov <bp@suse.de> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Petr Mladek <pmladek@suse.com> Cc: Sergey Senozhatsky <senozhatsky@chromium.org> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: John Ogness <john.ogness@linutronix.de> Reviewed-by: John Ogness <john.ogness@linutronix.de> Reviewed-by: Sergey Senozhatsky <senozhatsky@chromium.org> Reviewed-by: Petr Mladek <pmladek@suse.com> Signed-off-by: Petr Mladek <pmladek@suse.com> Link: https://lore.kernel.org/r/20220228220556.23484-1-rdunlap@infradead.org Signed-off-by: Sasha Levin <sashal@kernel.org>
2022-04-08perf/core: Fix address filter parser for multiple filtersAdrian Hunter1-0/+3
[ Upstream commit d680ff24e9e14444c63945b43a37ede7cd6958f9 ] Reset appropriate variables in the parser loop between parsing separate filters, so that they do not interfere with parsing the next filter. Fixes: 375637bc524952 ("perf/core: Introduce address range filtering") Signed-off-by: Adrian Hunter <adrian.hunter@intel.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lore.kernel.org/r/20220131072453.2839535-4-adrian.hunter@intel.com Signed-off-by: Sasha Levin <sashal@kernel.org>
2022-04-08rseq: Remove broken uapi field layout on 32-bit little endianMathieu Desnoyers1-4/+4
[ Upstream commit bfdf4e6208051ed7165b2e92035b4bf11f43eb63 ] The rseq rseq_cs.ptr.{ptr32,padding} uapi endianness handling is entirely wrong on 32-bit little endian: a preprocessor logic mistake wrongly uses the big endian field layout on 32-bit little endian architectures. Fortunately, those ptr32 accessors were never used within the kernel, and only meant as a convenience for user-space. Remove those and replace the whole rseq_cs union by a __u64 type, as this is the only thing really needed to express the ABI. Document how 32-bit architectures are meant to interact with this field. Fixes: ec9c82e03a74 ("rseq: uapi: Declare rseq_cs field as union, update includes") Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/20220127152720.25898-1-mathieu.desnoyers@efficios.com Signed-off-by: Sasha Levin <sashal@kernel.org>
2022-04-08rseq: Optimise rseq_get_rseq_cs() and clear_rseq_cs()Eric Dumazet1-0/+9
[ Upstream commit 5e0ccd4a3b01c5a71732a13186ca110a138516ea ] Commit ec9c82e03a74 ("rseq: uapi: Declare rseq_cs field as union, update includes") added regressions for our servers. Using copy_from_user() and clear_user() for 64bit values is suboptimal. We can use faster put_user() and get_user() on 64bit arches. Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Link: https://lkml.kernel.org/r/20210413203352.71350-4-eric.dumazet@gmail.com Signed-off-by: Sasha Levin <sashal@kernel.org>
2022-04-08sched/core: Export pelt_thermal_tpQais Yousef1-0/+1
[ Upstream commit 77cf151b7bbdfa3577b3c3f3a5e267a6c60a263b ] We can't use this tracepoint in modules without having the symbol exported first, fix that. Fixes: 765047932f15 ("sched/pelt: Add support to track thermal pressure") Signed-off-by: Qais Yousef <qais.yousef@arm.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/20211028115005.873539-1-qais.yousef@arm.com Signed-off-by: Sasha Levin <sashal@kernel.org>
2022-04-08sched/debug: Remove mpol_get/put and task_lock/unlock from sched_show_numaBharata B Rao1-10/+0
[ Upstream commit 28c988c3ec29db74a1dda631b18785958d57df4f ] The older format of /proc/pid/sched printed home node info which required the mempolicy and task lock around mpol_get(). However the format has changed since then and there is no need for sched_show_numa() any more to have mempolicy argument, asssociated mpol_get/put and task_lock/unlock. Remove them. Fixes: 397f2378f1361 ("sched/numa: Fix numa balancing stats in /proc/pid/sched") Signed-off-by: Bharata B Rao <bharata@amd.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com> Acked-by: Mel Gorman <mgorman@suse.de> Link: https://lore.kernel.org/r/20220118050515.2973-1-bharata@amd.com Signed-off-by: Sasha Levin <sashal@kernel.org>
2022-04-08watch_queue: Actually free the watchDavid Howells1-0/+1
[ Upstream commit 3d8dcf278b1ee1eff1e90be848fa2237db4c07a7 ] free_watch() does everything barring actually freeing the watch object. Fix this by adding the missing kfree. kmemleak produces a report something like the following. Note that as an address can be seen in the first word, the watch would appear to have gone through call_rcu(). BUG: memory leak unreferenced object 0xffff88810ce4a200 (size 96): comm "syz-executor352", pid 3605, jiffies 4294947473 (age 13.720s) hex dump (first 32 bytes): e0 82 48 0d 81 88 ff ff 00 00 00 00 00 00 00 00 ..H............. 80 a2 e4 0c 81 88 ff ff 00 00 00 00 00 00 00 00 ................ backtrace: [<ffffffff8214e6cc>] kmalloc include/linux/slab.h:581 [inline] [<ffffffff8214e6cc>] kzalloc include/linux/slab.h:714 [inline] [<ffffffff8214e6cc>] keyctl_watch_key+0xec/0x2e0 security/keys/keyctl.c:1800 [<ffffffff8214ec84>] __do_sys_keyctl+0x3c4/0x490 security/keys/keyctl.c:2016 [<ffffffff84493a25>] do_syscall_x64 arch/x86/entry/common.c:50 [inline] [<ffffffff84493a25>] do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80 [<ffffffff84600068>] entry_SYSCALL_64_after_hwframe+0x44/0xae Fixes: c73be61cede5 ("pipe: Add general notification queue support") Reported-and-tested-by: syzbot+6e2de48f06cdb2884bfc@syzkaller.appspotmail.com Signed-off-by: David Howells <dhowells@redhat.com> Signed-off-by: Sasha Levin <sashal@kernel.org>
2022-04-08watch_queue: Fix NULL dereference in error cleanupDavid Howells1-1/+1
[ Upstream commit a635415a064e77bcfbf43da413fd9dfe0bbed9cb ] In watch_queue_set_size(), the error cleanup code doesn't take account of the fact that __free_page() can't handle a NULL pointer when trying to free up buffer pages that did get allocated. Fix this by only calling __free_page() on the pages actually allocated. Without the fix, this can lead to something like the following: BUG: KASAN: null-ptr-deref in __free_pages+0x1f/0x1b0 mm/page_alloc.c:5473 Read of size 4 at addr 0000000000000034 by task syz-executor168/3599 ... Call Trace: <TASK> __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106 __kasan_report mm/kasan/report.c:446 [inline] kasan_report.cold+0x66/0xdf mm/kasan/report.c:459 check_region_inline mm/kasan/generic.c:183 [inline] kasan_check_range+0x13d/0x180 mm/kasan/generic.c:189 instrument_atomic_read include/linux/instrumented.h:71 [inline] atomic_read include/linux/atomic/atomic-instrumented.h:27 [inline] page_ref_count include/linux/page_ref.h:67 [inline] put_page_testzero include/linux/mm.h:717 [inline] __free_pages+0x1f/0x1b0 mm/page_alloc.c:5473 watch_queue_set_size+0x499/0x630 kernel/watch_queue.c:275 pipe_ioctl+0xac/0x2b0 fs/pipe.c:632 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:874 [inline] __se_sys_ioctl fs/ioctl.c:860 [inline] __x64_sys_ioctl+0x193/0x200 fs/ioctl.c:860 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x44/0xae Fixes: c73be61cede5 ("pipe: Add general notification queue support") Reported-and-tested-by: syzbot+d55757faa9b80590767b@syzkaller.appspotmail.com Signed-off-by: David Howells <dhowells@redhat.com> Reviewed-by: Fabio M. De Francesco <fmdefrancesco@gmail.com> Signed-off-by: Sasha Levin <sashal@kernel.org>
2022-04-08PM: suspend: fix return value of __setup handlerRandy Dunlap1-4/+4
[ Upstream commit 7a64ca17e4dd50d5f910769167f3553902777844 ] If an invalid option is given for "test_suspend=<option>", the entire string is added to init's environment, so return 1 instead of 0 from the __setup handler. Unknown kernel command line parameters "BOOT_IMAGE=/boot/bzImage-517rc5 test_suspend=invalid" and Run /sbin/init as init process with arguments: /sbin/init with environment: HOME=/ TERM=linux BOOT_IMAGE=/boot/bzImage-517rc5 test_suspend=invalid Fixes: 2ce986892faf ("PM / sleep: Enhance test_suspend option with repeat capability") Fixes: 27ddcc6596e5 ("PM / sleep: Add state field to pm_states[] entries") Fixes: a9d7052363a6 ("PM: Separate suspend to RAM functionality from core") Signed-off-by: Randy Dunlap <rdunlap@infradead.org> Reported-by: Igor Zhbanov <i.zhbanov@omprussia.ru> Link: lore.kernel.org/r/64644a2f-4a20-bab3-1e15-3b2cdd0defe3@omprussia.ru Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Signed-off-by: Sasha Levin <sashal@kernel.org>
2022-04-08PM: hibernate: fix __setup handler error handlingRandy Dunlap1-1/+1
[ Upstream commit ba7ffcd4c4da374b0f64666354eeeda7d3827131 ] If an invalid value is used in "resumedelay=<seconds>", it is silently ignored. Add a warning message and then let the __setup handler return 1 to indicate that the kernel command line option has been handled. Fixes: 317cf7e5e85e3 ("PM / hibernate: convert simple_strtoul to kstrtoul") Signed-off-by: Randy Dunlap <rdunlap@infradead.org> Reported-by: Igor Zhbanov <i.zhbanov@omprussia.ru> Link: lore.kernel.org/r/64644a2f-4a20-bab3-1e15-3b2cdd0defe3@omprussia.ru Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Signed-off-by: Sasha Levin <sashal@kernel.org>
2022-04-08audit: log AUDIT_TIME_* records only from rulesRichard Guy Briggs2-20/+71
[ Upstream commit 272ceeaea355214b301530e262a0df8600bfca95 ] AUDIT_TIME_* events are generated when there are syscall rules present that are not related to time keeping. This will produce noisy log entries that could flood the logs and hide events we really care about. Rather than immediately produce the AUDIT_TIME_* records, store the data in the context and log it at syscall exit time respecting the filter rules. Note: This eats the audit_buffer, unlike any others in show_special(). Please see https://bugzilla.redhat.com/show_bug.cgi?id=1991919 Fixes: 7e8eda734d30 ("ntp: Audit NTP parameters adjustment") Fixes: 2d87a0674bd6 ("timekeeping: Audit clock adjustments") Signed-off-by: Richard Guy Briggs <rgb@redhat.com> [PM: fixed style/whitespace issues] Signed-off-by: Paul Moore <paul@paul-moore.com> Signed-off-by: Sasha Levin <sashal@kernel.org>
2022-04-08ptrace: Check PTRACE_O_SUSPEND_SECCOMP permission on PTRACE_SEIZEJann Horn1-15/+32
commit ee1fee900537b5d9560e9f937402de5ddc8412f3 upstream. Setting PTRACE_O_SUSPEND_SECCOMP is supposed to be a highly privileged operation because it allows the tracee to completely bypass all seccomp filters on kernels with CONFIG_CHECKPOINT_RESTORE=y. It is only supposed to be settable by a process with global CAP_SYS_ADMIN, and only if that process is not subject to any seccomp filters at all. However, while these permission checks were done on the PTRACE_SETOPTIONS path, they were missing on the PTRACE_SEIZE path, which also sets user-specified ptrace flags. Move the permissions checks out into a helper function and let both ptrace_attach() and ptrace_setoptions() call it. Cc: stable@kernel.org Fixes: 13c4a90119d2 ("seccomp: add ptrace options for suspend/resume") Signed-off-by: Jann Horn <jannh@google.com> Link: https://lkml.kernel.org/r/20220319010838.1386861-1-jannh@google.com Signed-off-by: Eric W. Biederman <ebiederm@xmission.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-04-08locking/lockdep: Avoid potential access of invalid memory in lock_classWaiman Long1-9/+15
commit 61cc4534b6550997c97a03759ab46b29d44c0017 upstream. It was found that reading /proc/lockdep after a lockdep splat may potentially cause an access to freed memory if lockdep_unregister_key() is called after the splat but before access to /proc/lockdep [1]. This is due to the fact that graph_lock() call in lockdep_unregister_key() fails after the clearing of debug_locks by the splat process. After lockdep_unregister_key() is called, the lock_name may be freed but the corresponding lock_class structure still have a reference to it. That invalid memory pointer will then be accessed when /proc/lockdep is read by a user and a use-after-free (UAF) error will be reported if KASAN is enabled. To fix this problem, lockdep_unregister_key() is now modified to always search for a matching key irrespective of the debug_locks state and zap the corresponding lock class if a matching one is found. [1] https://lore.kernel.org/lkml/77f05c15-81b6-bddd-9650-80d5f23fe330@i-love.sakura.ne.jp/ Fixes: 8b39adbee805 ("locking/lockdep: Make lockdep_unregister_key() honor 'debug_locks' again") Reported-by: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp> Signed-off-by: Waiman Long <longman@redhat.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Bart Van Assche <bvanassche@acm.org> Cc: Cheng-Jui Wang <cheng-jui.wang@mediatek.com> Link: https://lkml.kernel.org/r/20220103023558.1377055-1-longman@redhat.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-04-08swiotlb: fix info leak with DMA_FROM_DEVICEHalil Pasic1-1/+2
commit ddbd89deb7d32b1fbb879f48d68fda1a8ac58e8e upstream. The problem I'm addressing was discovered by the LTP test covering cve-2018-1000204. A short description of what happens follows: 1) The test case issues a command code 00 (TEST UNIT READY) via the SG_IO interface with: dxfer_len == 524288, dxdfer_dir == SG_DXFER_FROM_DEV and a corresponding dxferp. The peculiar thing about this is that TUR is not reading from the device. 2) In sg_start_req() the invocation of blk_rq_map_user() effectively bounces the user-space buffer. As if the device was to transfer into it. Since commit a45b599ad808 ("scsi: sg: allocate with __GFP_ZERO in sg_build_indirect()") we make sure this first bounce buffer is allocated with GFP_ZERO. 3) For the rest of the story we keep ignoring that we have a TUR, so the device won't touch the buffer we prepare as if the we had a DMA_FROM_DEVICE type of situation. My setup uses a virtio-scsi device and the buffer allocated by SG is mapped by the function virtqueue_add_split() which uses DMA_FROM_DEVICE for the "in" sgs (here scatter-gather and not scsi generics). This mapping involves bouncing via the swiotlb (we need swiotlb to do virtio in protected guest like s390 Secure Execution, or AMD SEV). 4) When the SCSI TUR is done, we first copy back the content of the second (that is swiotlb) bounce buffer (which most likely contains some previous IO data), to the first bounce buffer, which contains all zeros. Then we copy back the content of the first bounce buffer to the user-space buffer. 5) The test case detects that the buffer, which it zero-initialized, ain't all zeros and fails. One can argue that this is an swiotlb problem, because without swiotlb we leak all zeros, and the swiotlb should be transparent in a sense that it does not affect the outcome (if all other participants are well behaved). Copying the content of the original buffer into the swiotlb buffer is the only way I can think of to make swiotlb transparent in such scenarios. So let's do just that if in doubt, but allow the driver to tell us that the whole mapped buffer is going to be overwritten, in which case we can preserve the old behavior and avoid the performance impact of the extra bounce. Signed-off-by: Halil Pasic <pasic@linux.ibm.com> Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-03-28rcu: Don't deboost before reporting expedited quiescent statePaul E. McKenney1-4/+5
commit 10c535787436d62ea28156a4b91365fd89b5a432 upstream. Currently rcu_preempt_deferred_qs_irqrestore() releases rnp->boost_mtx before reporting the expedited quiescent state. Under heavy real-time load, this can result in this function being preempted before the quiescent state is reported, which can in turn prevent the expedited grace period from completing. Tim Murray reports that the resulting expedited grace periods can take hundreds of milliseconds and even more than one second, when they should normally complete in less than a millisecond. This was fine given that there were no particular response-time constraints for synchronize_rcu_expedited(), as it was designed for throughput rather than latency. However, some users now need sub-100-millisecond response-time constratints. This patch therefore follows Neeraj's suggestion (seconded by Tim and by Uladzislau Rezki) of simply reversing the two operations. Reported-by: Tim Murray <timmurray@google.com> Reported-by: Joel Fernandes <joelaf@google.com> Reported-by: Neeraj Upadhyay <quic_neeraju@quicinc.com> Reviewed-by: Neeraj Upadhyay <quic_neeraju@quicinc.com> Reviewed-by: Uladzislau Rezki (Sony) <urezki@gmail.com> Tested-by: Tim Murray <timmurray@google.com> Cc: Todd Kjos <tkjos@google.com> Cc: Sandeep Patil <sspatil@google.com> Cc: <stable@vger.kernel.org> # 5.4.x Signed-off-by: Paul E. McKenney <paulmck@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-03-28cgroup-v1: Correct privileges check in release_agent writesMichal Koutný1-2/+4
commit 467a726b754f474936980da793b4ff2ec3e382a7 upstream. The idea is to check: a) the owning user_ns of cgroup_ns, b) capabilities in init_user_ns. The commit 24f600856418 ("cgroup-v1: Require capabilities to set release_agent") got this wrong in the write handler of release_agent since it checked user_ns of the opener (may be different from the owning user_ns of cgroup_ns). Secondly, to avoid possibly confused deputy, the capability of the opener must be checked. Fixes: 24f600856418 ("cgroup-v1: Require capabilities to set release_agent") Cc: stable@vger.kernel.org Link: https://lore.kernel.org/stable/20220216121142.GB30035@blackbody.suse.cz/ Signed-off-by: Michal Koutný <mkoutny@suse.com> Reviewed-by: Masami Ichikawa(CIP) <masami.ichikawa@cybertrust.co.jp> Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-03-28cgroup: Use open-time cgroup namespace for process migration perm checksTejun Heo2-10/+24
commit e57457641613fef0d147ede8bd6a3047df588b95 upstream. cgroup process migration permission checks are performed at write time as whether a given operation is allowed or not is dependent on the content of the write - the PID. This currently uses current's cgroup namespace which is a potential security weakness as it may allow scenarios where a less privileged process tricks a more privileged one into writing into a fd that it created. This patch makes cgroup remember the cgroup namespace at the time of open and uses it for migration permission checks instad of current's. Note that this only applies to cgroup2 as cgroup1 doesn't have namespace support. This also fixes a use-after-free bug on cgroupns reported in https://lore.kernel.org/r/00000000000048c15c05d0083397@google.com Note that backporting this fix also requires the preceding patch. Reported-by: "Eric W. Biederman" <ebiederm@xmission.com> Suggested-by: Linus Torvalds <torvalds@linuxfoundation.org> Cc: Michal Koutný <mkoutny@suse.com> Cc: Oleg Nesterov <oleg@redhat.com> Reviewed-by: Michal Koutný <mkoutny@suse.com> Reported-by: syzbot+50f5cf33a284ce738b62@syzkaller.appspotmail.com Link: https://lore.kernel.org/r/00000000000048c15c05d0083397@google.com Fixes: 5136f6365ce3 ("cgroup: implement "nsdelegate" mount option") Signed-off-by: Tejun Heo <tj@kernel.org> [mkoutny: v5.10: duplicate ns check in procs/threads write handler, adjust context] Signed-off-by: Michal Koutný <mkoutny@suse.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-03-28cgroup: Allocate cgroup_file_ctx for kernfs_open_file->privTejun Heo3-32/+65
commit 0d2b5955b36250a9428c832664f2079cbf723bec upstream. of->priv is currently used by each interface file implementation to store private information. This patch collects the current two private data usages into struct cgroup_file_ctx which is allocated and freed by the common path. This allows generic private data which applies to multiple files, which will be used to in the following patch. Note that cgroup_procs iterator is now embedded as procs.iter in the new cgroup_file_ctx so that it doesn't need to be allocated and freed separately. v2: union dropped from cgroup_file_ctx and the procs iterator is embedded in cgroup_file_ctx as suggested by Linus. v3: Michal pointed out that cgroup1's procs pidlist uses of->priv too. Converted. Didn't change to embedded allocation as cgroup1 pidlists get stored for caching. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Reviewed-by: Michal Koutný <mkoutny@suse.com> [mkoutny: v5.10: modify cgroup.pressure handlers, adjust context] Signed-off-by: Michal Koutný <mkoutny@suse.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-03-16watch_queue: Fix filter limit checkDavid Howells1-2/+2
commit c993ee0f9f81caf5767a50d1faeba39a0dc82af2 upstream. In watch_queue_set_filter(), there are a couple of places where we check that the filter type value does not exceed what the type_filter bitmap can hold. One place calculates the number of bits by: if (tf[i].type >= sizeof(wfilter->type_filter) * 8) which is fine, but the second does: if (tf[i].type >= sizeof(wfilter->type_filter) * BITS_PER_LONG) which is not. This can lead to a couple of out-of-bounds writes due to a too-large type: (1) __set_bit() on wfilter->type_filter (2) Writing more elements in wfilter->filters[] than we allocated. Fix this by just using the proper WATCH_TYPE__NR instead, which is the number of types we actually know about. The bug may cause an oops looking something like: BUG: KASAN: slab-out-of-bounds in watch_queue_set_filter+0x659/0x740 Write of size 4 at addr ffff88800d2c66bc by task watch_queue_oob/611 ... Call Trace: <TASK> dump_stack_lvl+0x45/0x59 print_address_description.constprop.0+0x1f/0x150 ... kasan_report.cold+0x7f/0x11b ... watch_queue_set_filter+0x659/0x740 ... __x64_sys_ioctl+0x127/0x190 do_syscall_64+0x43/0x90 entry_SYSCALL_64_after_hwframe+0x44/0xae Allocated by task 611: kasan_save_stack+0x1e/0x40 __kasan_kmalloc+0x81/0xa0 watch_queue_set_filter+0x23a/0x740 __x64_sys_ioctl+0x127/0x190 do_syscall_64+0x43/0x90 entry_SYSCALL_64_after_hwframe+0x44/0xae The buggy address belongs to the object at ffff88800d2c66a0 which belongs to the cache kmalloc-32 of size 32 The buggy address is located 28 bytes inside of 32-byte region [ffff88800d2c66a0, ffff88800d2c66c0) Fixes: c73be61cede5 ("pipe: Add general notification queue support") Reported-by: Jann Horn <jannh@google.com> Signed-off-by: David Howells <dhowells@redhat.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-03-16watch_queue: Make comment about setting ->defunct more accurateDavid Howells1-1/+1
commit 4edc0760412b0c4ecefc7e02cb855b310b122825 upstream. watch_queue_clear() has a comment stating that setting ->defunct to true preventing new additions as well as preventing notifications. Whilst the latter is true, the first bit is superfluous since at the time this function is called, the pipe cannot be accessed to add new event sources. Remove the "new additions" bit from the comment. Fixes: c73be61cede5 ("pipe: Add general notification queue support") Reported-by: Jann Horn <jannh@google.com> Signed-off-by: David Howells <dhowells@redhat.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-03-16watch_queue: Fix lack of barrier/sync/lock between post and readDavid Howells1-1/+1
commit 2ed147f015af2b48f41c6f0b6746aa9ea85c19f3 upstream. There's nothing to synchronise post_one_notification() versus pipe_read(). Whilst posting is done under pipe->rd_wait.lock, the reader only takes pipe->mutex which cannot bar notification posting as that may need to be made from contexts that cannot sleep. Fix this by setting pipe->head with a barrier in post_one_notification() and reading pipe->head with a barrier in pipe_read(). If that's not sufficient, the rd_wait.lock will need to be taken, possibly in a ->confirm() op so that it only applies to notifications. The lock would, however, have to be dropped before copy_page_to_iter() is invoked. Fixes: c73be61cede5 ("pipe: Add general notification queue support") Reported-by: Jann Horn <jannh@google.com> Signed-off-by: David Howells <dhowells@redhat.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-03-16watch_queue: Free the alloc bitmap when the watch_queue is torn downDavid Howells1-0/+1
commit 7ea1a0124b6da246b5bc8c66cddaafd36acf3ecb upstream. Free the watch_queue note allocation bitmap when the watch_queue is destroyed. Fixes: c73be61cede5 ("pipe: Add general notification queue support") Reported-by: Jann Horn <jannh@google.com> Signed-off-by: David Howells <dhowells@redhat.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-03-16watch_queue: Fix the alloc bitmap size to reflect notes allocatedDavid Howells1-1/+2
commit 3b4c0371928c17af03e8397ac842346624017ce6 upstream. Currently, watch_queue_set_size() sets the number of notes available in wqueue->nr_notes according to the number of notes allocated, but sets the size of the bitmap to the unrounded number of notes originally asked for. Fix this by setting the bitmap size to the number of notes we're actually going to make available (ie. the number allocated). Fixes: c73be61cede5 ("pipe: Add general notification queue support") Reported-by: Jann Horn <jannh@google.com> Signed-off-by: David Howells <dhowells@redhat.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-03-16watch_queue: Fix to always request a pow-of-2 pipe ring sizeDavid Howells1-1/+1
commit 96a4d8912b28451cd62825fd7caa0e66e091d938 upstream. The pipe ring size must always be a power of 2 as the head and tail pointers are masked off by AND'ing with the size of the ring - 1. watch_queue_set_size(), however, lets you specify any number of notes between 1 and 511. This number is passed through to pipe_resize_ring() without checking/forcing its alignment. Fix this by rounding the number of slots required up to the nearest power of two. The request is meant to guarantee that at least that many notifications can be generated before the queue is full, so rounding down isn't an option, but, alternatively, it may be better to give an error if we aren't allowed to allocate that much ring space. Fixes: c73be61cede5 ("pipe: Add general notification queue support") Reported-by: Jann Horn <jannh@google.com> Signed-off-by: David Howells <dhowells@redhat.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-03-16watch_queue: Fix to release page in ->release()David Howells1-0/+1
commit c1853fbadcba1497f4907971e7107888e0714c81 upstream. When a pipe ring descriptor points to a notification message, the refcount on the backing page is incremented by the generic get function, but the release function, which marks the bitmap, doesn't drop the page ref. Fix this by calling generic_pipe_buf_release() at the end of watch_queue_pipe_buf_release(). Fixes: c73be61cede5 ("pipe: Add general notification queue support") Reported-by: Jann Horn <jannh@google.com> Signed-off-by: David Howells <dhowells@redhat.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-03-16tracing: Ensure trace buffer is at least 4096 bytes largeSven Schnelle1-4/+6
[ Upstream commit 7acf3a127bb7c65ff39099afd78960e77b2ca5de ] Booting the kernel with 'trace_buf_size=1' give a warning at boot during the ftrace selftests: [ 0.892809] Running postponed tracer tests: [ 0.892893] Testing tracer function: [ 0.901899] Callback from call_rcu_tasks_trace() invoked. [ 0.983829] Callback from call_rcu_tasks_rude() invoked. [ 1.072003] .. bad ring buffer .. corrupted trace buffer .. [ 1.091944] Callback from call_rcu_tasks() invoked. [ 1.097695] PASSED [ 1.097701] Testing dynamic ftrace: .. filter failed count=0 ..FAILED! [ 1.353474] ------------[ cut here ]------------ [ 1.353478] WARNING: CPU: 0 PID: 1 at kernel/trace/trace.c:1951 run_tracer_selftest+0x13c/0x1b0 Therefore enforce a minimum of 4096 bytes to make the selftest pass. Link: https://lkml.kernel.org/r/20220214134456.1751749-1-svens@linux.ibm.com Signed-off-by: Sven Schnelle <svens@linux.ibm.com> Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org> Signed-off-by: Sasha Levin &l