Hi Rafael, Wonhong, Todays linux-next breaks rather spectacularly for drivers using runtime PM. The culprit seems to be this commit: commit 7d24068e144adc03b805806645d732cf79488717 Author: Wonhong Kwon <wonhongkwon@xxxxxxxxx> Date: Tue Oct 6 10:10:20 2015 +0900 PM / hibernate: Move pm_init/pm_disk_init to late_initcall_sync pm_init is being invoked by core_initcall and hibernate_image_size_init calculates preferred image size (image_size) based on total pages (totalram_pages). This totalram_pages can be modified during various initcall-s phase and this can cause miscalculated image_size. For example, when CMA is being used, init_cma_reserved_pageblock tries to change the totalram_pages and this job is done during core_initcall. In order words, the totalram_pages doesn't take CMA reserved pages into account when image_size is calculated and it can be too small. Move pm_init and pm_disk_init to late_initcall_sync so that it happens after all other initcall-s change the totalram_pages. Reported-by: Sangseok Lee <sangseok.lee@xxxxxxx> Signed-off-by: Wonhong Kwon <wonhong.kwon@xxxxxxx> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx> I can't reply to it directly because I don't have it in any of my mail boxes (it seems to have been sent only to the linux-pm mailing list, even Google finds only a single match). Here's an extract of the oops: [ 1.395928] Unable to handle kernel NULL pointer dereference at virtual address 00000100 [ 1.404013] pgd = ffffffc000e0e000 [ 1.407417] [00000100] *pgd=000000013c007003, *pud=000000013c007003, *pmd=000000013c008003, *pte=0060000050041707 [ 1.417746] Internal error: Oops: 96000005 [#1] PREEMPT SMP [ 1.423316] Modules linked in: [ 1.426400] CPU: 0 PID: 1 Comm: swapper/0 Not tainted 4.3.0-rc5-next-20151015+ #1338 [ 1.434138] Hardware name: NVIDIA Tegra210 P2371 (P2180/P2597) reference board (DT) [ 1.441789] task: ffffffc0bc0a8000 ti: ffffffc0bc084000 task.ti: ffffffc0bc084000 [ 1.449280] PC is at __queue_work+0x2c/0x240 [ 1.453551] LR is at queue_work_on+0x60/0x78 ... [ 1.836517] Call trace: [ 1.838968] [<ffffffc0000b4134>] __queue_work+0x2c/0x240 [ 1.844280] [<ffffffc0000b43a4>] queue_work_on+0x5c/0x78 [ 1.849599] [<ffffffc00052e508>] rpm_idle+0xc0/0x140 [ 1.854565] [<ffffffc00052e5dc>] __pm_runtime_idle+0x54/0x98 [ 1.860229] [<ffffffc00052414c>] driver_probe_device+0x164/0x2f8 [ 1.866236] [<ffffffc000524378>] __driver_attach+0x98/0xa0 [ 1.871724] [<ffffffc00052231c>] bus_for_each_dev+0x5c/0xa0 [ 1.877294] [<ffffffc000523ab4>] driver_attach+0x1c/0x28 [ 1.882608] [<ffffffc0005236e4>] bus_add_driver+0x1cc/0x238 [ 1.888180] [<ffffffc000524b1c>] driver_register+0x5c/0xf8 [ 1.893675] [<ffffffc000431800>] mipi_dsi_driver_register_full+0x50/0x60 [ 1.900374] [<ffffffc000ba1570>] panel_simple_init+0x2c/0x44 [ 1.906035] [<ffffffc000082934>] do_one_initcall+0x8c/0x1a0 [ 1.911612] [<ffffffc000b80aa8>] kernel_init_freeable+0x150/0x1f8 [ 1.917711] [<ffffffc0007f78fc>] kernel_init+0xc/0xe0 Instrumenting the code shows that pm_wq (passed to queue_work in the rpm_idle() function) is NULL at this point. This matches up with the change done in the above-mentioned commit, since now pm_wq only gets initialized at late_initcall time, whereas all built-in drivers will already be probed at device_initcall time. So I suspect that this is going to cause crashes on a whole lot of systems (essentially every system that tries to use runtime PM from a built-in driver). Given the commit message I suspect that the right fix would be to split pm_init() into two functions, one that initializes the hibernation image and another with the PM core initialization. The pm_hibernate_init() is probably going to work fine as late_initcall (I assume this was tested) but the rest should probably stay at core_initcall. I can provide a patch for the latter if everyone agrees that it's the right thing, but in the meantime, can you please drop the above patch from your tree to unbreak linux-next for all affected users? Thanks, Thierry
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