From f303fccb82928790ec58eea82722bd5c54d300b3 Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Tue, 9 Feb 2016 17:59:38 -0500 Subject: workqueue: implement "workqueue.debug_force_rr_cpu" debug feature Workqueue used to guarantee local execution for work items queued without explicit target CPU. The guarantee is gone now which can break some usages in subtle ways. To flush out those cases, this patch implements a debug feature which forces round-robin CPU selection for all such work items. The debug feature defaults to off and can be enabled with a kernel parameter. The default can be flipped with a debug config option. If you hit this commit during bisection, please refer to 041bd12e272c ("Revert "workqueue: make sure delayed work run in local cpu"") for more information and ping me. Signed-off-by: Tejun Heo --- lib/Kconfig.debug | 15 +++++++++++++++ 1 file changed, 15 insertions(+) (limited to 'lib') diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug index ecb9e75614bf..8bfd1aca7a3d 100644 --- a/lib/Kconfig.debug +++ b/lib/Kconfig.debug @@ -1400,6 +1400,21 @@ config RCU_EQS_DEBUG endmenu # "RCU Debugging" +config DEBUG_WQ_FORCE_RR_CPU + bool "Force round-robin CPU selection for unbound work items" + depends on DEBUG_KERNEL + default n + help + Workqueue used to implicitly guarantee that work items queued + without explicit CPU specified are put on the local CPU. This + guarantee is no longer true and while local CPU is still + preferred work items may be put on foreign CPUs. Kernel + parameter "workqueue.debug_force_rr_cpu" is added to force + round-robin CPU selection to flush out usages which depend on the + now broken guarantee. This config option enables the debug + feature by default. When enabled, memory and cache locality will + be impacted. + config DEBUG_BLOCK_EXT_DEVT bool "Force extended block device numbers and spread them" depends on DEBUG_KERNEL -- cgit v1.2.3 From 7707535ab95e2231b6d7f2bfb4f27558e83c4dc2 Mon Sep 17 00:00:00 2001 From: Yang Shi Date: Thu, 11 Feb 2016 16:12:55 -0800 Subject: ubsan: cosmetic fix to Kconfig text When enabling UBSAN_SANITIZE_ALL, the kernel image size gets increased significantly (~3x). So, it sounds better to have some note in Kconfig. And, fixed a typo. Signed-off-by: Yang Shi Acked-by: Andrey Ryabinin Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- lib/Kconfig.ubsan | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) (limited to 'lib') diff --git a/lib/Kconfig.ubsan b/lib/Kconfig.ubsan index 49518fb48cab..e07c1ba9ba13 100644 --- a/lib/Kconfig.ubsan +++ b/lib/Kconfig.ubsan @@ -18,6 +18,8 @@ config UBSAN_SANITIZE_ALL This option activates instrumentation for the entire kernel. If you don't enable this option, you have to explicitly specify UBSAN_SANITIZE := y for the files/directories you want to check for UB. + Enabling this option will get kernel image size increased + significantly. config UBSAN_ALIGNMENT bool "Enable checking of pointers alignment" @@ -25,5 +27,5 @@ config UBSAN_ALIGNMENT default y if !HAVE_EFFICIENT_UNALIGNED_ACCESS help This option enables detection of unaligned memory accesses. - Enabling this option on architectures that support unalligned + Enabling this option on architectures that support unaligned accesses may produce a lot of false positives. -- cgit v1.2.3 From 7eb391299419a03cbe0fa5ab0e6b0932e42c7a36 Mon Sep 17 00:00:00 2001 From: "Jason A. Donenfeld" Date: Thu, 11 Feb 2016 16:13:00 -0800 Subject: vsprintf: kptr_restrict is okay in IRQ when 2 The kptr_restrict flag, when set to 1, only prints the kernel address when the user has CAP_SYSLOG. When it is set to 2, the kernel address is always printed as zero. When set to 1, this needs to check whether or not we're in IRQ. However, when set to 2, this check is unneccessary, and produces confusing results in dmesg. Thus, only make sure we're not in IRQ when mode 1 is used, but not mode 2. [akpm@linux-foundation.org: coding-style fixes] Signed-off-by: Jason A. Donenfeld Cc: Rasmus Villemoes Cc: Kees Cook Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- lib/vsprintf.c | 26 +++++++++++++------------- 1 file changed, 13 insertions(+), 13 deletions(-) (limited to 'lib') diff --git a/lib/vsprintf.c b/lib/vsprintf.c index 48ff9c36644d..f44e178e6ede 100644 --- a/lib/vsprintf.c +++ b/lib/vsprintf.c @@ -1590,22 +1590,23 @@ char *pointer(const char *fmt, char *buf, char *end, void *ptr, return buf; } case 'K': - /* - * %pK cannot be used in IRQ context because its test - * for CAP_SYSLOG would be meaningless. - */ - if (kptr_restrict && (in_irq() || in_serving_softirq() || - in_nmi())) { - if (spec.field_width == -1) - spec.field_width = default_width; - return string(buf, end, "pK-error", spec); - } - switch (kptr_restrict) { case 0: /* Always print %pK values */ break; case 1: { + const struct cred *cred; + + /* + * kptr_restrict==1 cannot be used in IRQ context + * because its test for CAP_SYSLOG would be meaningless. + */ + if (in_irq() || in_serving_softirq() || in_nmi()) { + if (spec.field_width == -1) + spec.field_width = default_width; + return string(buf, end, "pK-error", spec); + } + /* * Only print the real pointer value if the current * process has CAP_SYSLOG and is running with the @@ -1615,8 +1616,7 @@ char *pointer(const char *fmt, char *buf, char *end, void *ptr, * leak pointer values if a binary opens a file using * %pK and then elevates privileges before reading it. */ - const struct cred *cred = current_cred(); - + cred = current_cred(); if (!has_capability_noaudit(current, CAP_SYSLOG) || !uid_eq(cred->euid, cred->uid) || !gid_eq(cred->egid, cred->gid)) -- cgit v1.2.3