From: Jarrett Farnitano Date: Thu, 14 Jun 2018 22:26:31 +0000 (-0700) Subject: kexec: yield to scheduler when loading kimage segments X-Git-Tag: v4.19~775^2~21 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=a8311f647e419675f6ecba9f4284080fd38a0a37;p=platform%2Fkernel%2Flinux-rpi3.git kexec: yield to scheduler when loading kimage segments Without yielding while loading kimage segments, a large initrd will block all other work on the CPU performing the load until it is completed. For example loading an initrd of 200MB on a low power single core system will lock up the system for a few seconds. To increase system responsiveness to other tasks at that time, call cond_resched() in both the crash kernel and normal kernel segment loading loops. I did run into a practical problem. Hardware watchdogs on embedded systems can have short timers on the order of seconds. If the system is locked up for a few seconds with only a single core available, the watchdog may not be pet in a timely fashion. If this happens, the hardware watchdog will fire and reset the system. This really only becomes a problem when you are working with a single core, a decently sized initrd, and have a constrained hardware watchdog. Link: http://lkml.kernel.org/r/1528738546-3328-1-git-send-email-jmf@amazon.com Signed-off-by: Jarrett Farnitano Reviewed-by: "Eric W. Biederman" Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- diff --git a/kernel/kexec_core.c b/kernel/kexec_core.c index 20fef1a..23a83a4 100644 --- a/kernel/kexec_core.c +++ b/kernel/kexec_core.c @@ -829,6 +829,8 @@ static int kimage_load_normal_segment(struct kimage *image, else buf += mchunk; mbytes -= mchunk; + + cond_resched(); } out: return result; @@ -893,6 +895,8 @@ static int kimage_load_crash_segment(struct kimage *image, else buf += mchunk; mbytes -= mchunk; + + cond_resched(); } out: return result;