On Mon, May 20, 2019 at 02:09:05PM -0700, Johannes Erdfelt wrote: > On Mon, May 20, 2019, Joe Lawrence <joe.lawre...@redhat.com> wrote: > > [ fixed jeyu's email address ] > > Thank you, the bounce message made it seem like my mail server was > blocked and not that the address didn't exist. > > I think MAINTAINERS needs an update since it still has the @redhat.com > address.
I think you must have been looking at an old version. [(v5.2-rc1)] ~/git/linux $ grep jeyu MAINTAINERS M: Jessica Yu <j...@kernel.org> > > On 5/20/19 3:49 PM, Johannes Erdfelt wrote: > > > [ ... snip ... ] > > > > > > I have put together a test case that can reproduce the crash using > > > KVM. The tarball includes a minimal kernel and initramfs, along with > > > a script to run qemu and the .config used to build the kernel. By > > > default it will attempt to reproduce by loading multiple livepatches > > > at the same time. Passing 'test=ftrace' to the script will attempt to > > > reproduce by racing with ftrace. > > > > > > My test setup reproduces the race and oops more reliably by loading > > > multiple livepatches at the same time than with the ftrace method. It's > > > not 100% reproducible, so the test case may need to be run multiple > > > times. > > > > > > It can be found here (not attached because of its size): > > > http://johannes.erdfelt.com/5.2.0-rc1-a188339ca5-livepatch-race.tar.gz > > > > Hi Johannes, > > > > This is cool way to distribute the repro kernel, modules, etc! > > This oops was common in our production environment and was particularly > annoying since livepatches would load at boot and early enough to happen > before networking and SSH were started. > > Unfortunately it was difficult to reproduce on other hardware (changing > the timing just enough) and our production environment is very > complicated. > > I spent more time than I'd like to admit trying to reproduce this fairly > reliably. I knew that I needed to help make it as easy as possible to > reproduce to root cause it and for others to take a look at it as well. Can you try this patch (completely untested)? diff --git a/kernel/livepatch/core.c b/kernel/livepatch/core.c index 91cd519756d3..2d17e6e364b5 100644 --- a/kernel/livepatch/core.c +++ b/kernel/livepatch/core.c @@ -30,6 +30,7 @@ #include <linux/elf.h> #include <linux/moduleloader.h> #include <linux/completion.h> +#include <linux/memory.h> #include <asm/cacheflush.h> #include "core.h" #include "patch.h" @@ -730,16 +731,21 @@ static int klp_init_object_loaded(struct klp_patch *patch, struct klp_func *func; int ret; + mutex_lock(&text_mutex); + module_disable_ro(patch->mod); ret = klp_write_object_relocations(patch->mod, obj); if (ret) { module_enable_ro(patch->mod, true); + mutex_unlock(&text_mutex); return ret; } arch_klp_init_object_loaded(patch, obj); module_enable_ro(patch->mod, true); + mutex_unlock(&text_mutex); + klp_for_each_func(obj, func) { ret = klp_find_object_symbol(obj->name, func->old_name, func->old_sympos, diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c index a12aff849c04..8259d4ba8b00 100644 --- a/kernel/trace/ftrace.c +++ b/kernel/trace/ftrace.c @@ -34,6 +34,7 @@ #include <linux/hash.h> #include <linux/rcupdate.h> #include <linux/kprobes.h> +#include <linux/memory.h> #include <trace/events/sched.h> @@ -2610,10 +2611,12 @@ static void ftrace_run_update_code(int command) { int ret; + mutex_lock(&text_mutex); + ret = ftrace_arch_code_modify_prepare(); FTRACE_WARN_ON(ret); if (ret) - return; + goto out_unlock; /* * By default we use stop_machine() to modify the code. @@ -2625,6 +2628,9 @@ static void ftrace_run_update_code(int command) ret = ftrace_arch_code_modify_post_process(); FTRACE_WARN_ON(ret); + +out_unlock: + mutex_unlock(&text_mutex); } static void ftrace_run_modify_code(struct ftrace_ops *ops, int command, @@ -5776,6 +5782,7 @@ void ftrace_module_enable(struct module *mod) struct ftrace_page *pg; mutex_lock(&ftrace_lock); + mutex_lock(&text_mutex); if (ftrace_disabled) goto out_unlock; @@ -5837,6 +5844,7 @@ void ftrace_module_enable(struct module *mod) ftrace_arch_code_modify_post_process(); out_unlock: + mutex_unlock(&text_mutex); mutex_unlock(&ftrace_lock); process_cached_mods(mod->name);
