From a46c524ce3b6e37161fc1956a3e7a8083f00770d Mon Sep 17 00:00:00 2001 From: Thomas Orgis Date: Mon, 9 Jul 2018 14:19:27 +0200 Subject: [PATCH] suspend: resume_usr_delay: headstart for kernel threads This applies the idea of https://askubuntu.com/questions/505779/suspending-with-root-on-usb in the hope that it may help with the random [13807.451872] EXT4-fs warning (device dm-4): ext4_end_bio:323: I/O error 10 writing to inode 3409454 (offset 0 size 0 starting block 19793351) [13807.451878] Buffer I/O error on device dm-4, logical block 19793351 [13807.451897] EXT4-fs warning (device dm-4): ext4_end_bio:323: I/O error 10 writing to inode 3409454 (offset 1867776 size 4096 starting block 19793352) [13807.451900] Buffer I/O error on device dm-4, logical block 19793352 I get on a SD card connected via USB, used as /home storag via encrypted LVM. My resume sequence does not really mirror what the OP had there, with the device not vanishing and reappearing in the logs, but _something_ is not ready yet, apparently. These I/O errors sometimes lead to read-only re-mounts, so there is damage involved. With the patch and a delay of 1000 ms, I did not observe the I/O again, so far. This all is a hack that hopefully points to the relevant kernel code that causes writes of the I/O layer before some driver is ready for it. --- kernel/power/hibernate.c | 11 ++++++++++- kernel/power/suspend.c | 11 +++++++++++ kernel/sysctl.c | 9 +++++++++ 3 files changed, 30 insertions(+), 1 deletion(-) diff --git a/kernel/power/hibernate.c b/kernel/power/hibernate.c index 9c85c7822383..18b93af401fd 100644 --- a/kernel/power/hibernate.c +++ b/kernel/power/hibernate.c @@ -775,7 +775,7 @@ int hibernate(void) return error; } - +extern unsigned int resume_usr_delay; /** * software_resume - Resume from a saved hibernation image. * @@ -891,6 +891,15 @@ static int software_resume(void) if (error) goto Close_Finish; error = load_image_and_restore(); + if (resume_usr_delay) { + /* Give kernel threads a head start, such that usb-storage + * can detect devices before syslog attempts to write log + * messages from the suspend code. + */ + thaw_kernel_threads(); + pr_info("PM: Sleeping for %d milliseconds.\n", resume_usr_delay); + msleep(resume_usr_delay); + } thaw_processes(); Finish: __pm_notifier_call_chain(PM_POST_RESTORE, nr_calls, NULL); diff --git a/kernel/power/suspend.c b/kernel/power/suspend.c index 87331565e505..d46b1cea2e70 100644 --- a/kernel/power/suspend.c +++ b/kernel/power/suspend.c @@ -520,6 +520,8 @@ int suspend_devices_and_enter(suspend_state_t state) goto Resume_devices; } +unsigned int resume_usr_delay = 0; + /** * suspend_finish - Clean up before finishing the suspend sequence. * @@ -528,6 +530,15 @@ int suspend_devices_and_enter(suspend_state_t state) */ static void suspend_finish(void) { + if (resume_usr_delay) { + /* Give kernel threads a head start, such that usb-storage + * can detect devices before syslog attempts to write log + * messages from the suspend code. + */ + thaw_kernel_threads(); + pr_info("PM: Sleeping for %d milliseconds.\n", resume_usr_delay); + msleep(resume_usr_delay); + } suspend_thaw_processes(); pm_notifier_call_chain(PM_POST_SUSPEND); pm_restore_console(); diff --git a/kernel/sysctl.c b/kernel/sysctl.c index 2d9837c0aff4..2911897a5cc6 100644 --- a/kernel/sysctl.c +++ b/kernel/sysctl.c @@ -308,6 +308,8 @@ static int min_extfrag_threshold; static int max_extfrag_threshold = 1000; #endif +extern unsigned int resume_usr_delay; + static struct ctl_table kern_table[] = { { .procname = "sched_child_runs_first", @@ -1873,6 +1875,13 @@ static struct ctl_table debug_table[] = { .extra2 = &one, }, #endif + { + .procname = "resume_usr_delay", + .data = &resume_usr_delay, + .maxlen = sizeof(unsigned int), + .mode = 0644, + .proc_handler = proc_dointvec, + }, { } }; -- 2.17.1