From a5bde5d8fde8a8cb28e59a672d5ddc5b9c1e7656 Mon Sep 17 00:00:00 2001 From: Breno Leitao Date: Wed, 5 Aug 2026 07:52:36 -0700 Subject: workqueue: skip the node_nr_active update for non-unbound workqueues apply_wqattrs_commit() updates node_nr_active->max unconditionally. wq->node_nr_active[] is only allocated for unbound workqueues, so guard the call before per-cpu workqueues start using this path. No functional change: only unbound workqueues reach apply_wqattrs_*() today. Signed-off-by: Breno Leitao Signed-off-by: Tejun Heo --- arch/x86/lib/usercopy.c | 55 +++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 55 insertions(+) create mode 100644 arch/x86/lib/usercopy.c (limited to 'arch/x86/lib/usercopy.c') diff --git a/arch/x86/lib/usercopy.c b/arch/x86/lib/usercopy.c new file mode 100644 index 000000000..24b48af27 --- /dev/null +++ b/arch/x86/lib/usercopy.c @@ -0,0 +1,55 @@ +/* + * User address space access functions. + * + * For licencing details see kernel-base/COPYING + */ + +#include +#include +#include + +#include + +/** + * copy_from_user_nmi - NMI safe copy from user + * @to: Pointer to the destination buffer + * @from: Pointer to a user space address of the current task + * @n: Number of bytes to copy + * + * Returns: The number of not copied bytes. 0 is success, i.e. all bytes copied + * + * Contrary to other copy_from_user() variants this function can be called + * from NMI context. Despite the name it is not restricted to be called + * from NMI context. It is safe to be called from any other context as + * well. It disables pagefaults across the copy which means a fault will + * abort the copy. + * + * For NMI context invocations this relies on the nested NMI work to allow + * atomic faults from the NMI path; the nested NMI paths are careful to + * preserve CR2. + */ +unsigned long +copy_from_user_nmi(void *to, const void __user *from, unsigned long n) +{ + unsigned long ret; + + if (!__access_ok(from, n)) + return n; + + if (!nmi_uaccess_okay()) + return n; + + /* + * Even though this function is typically called from NMI/IRQ context + * disable pagefaults so that its behaviour is consistent even when + * called from other contexts. + */ + pagefault_disable(); + instrument_copy_from_user_before(to, from, n); + ret = raw_copy_from_user(to, from, n); + instrument_copy_from_user_after(to, from, n, ret); + pagefault_enable(); + + return ret; +} +EXPORT_SYMBOL_GPL(copy_from_user_nmi); -- cgit v1.3.1