Dear Thierry, > -----Original Message----- > From: Thierry Reding [mailto:thierry.reding@xxxxxxxxx] > Sent: Thursday, October 15, 2015 6:22 PM > To: Rafael J. Wysocki; Wonhong Kwon > Cc: Len Brown; Pavel Machek; linux-next@xxxxxxxxxxxxxxx; linux- > pm@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx > Subject: Runtime PM causes oops on next-20151015 > > 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). I should've considered rumtime PM. Really sorry for bothering you. > > 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 agree that rest of pm_init() should stay at core_initcall and only hibernation_image_size_init() goes to late_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 -- To unsubscribe from this list: send the line "unsubscribe linux-next" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
