On Tue, 11 May 2010, Matt Reimer wrote: > >> or has a consensus about how to fix this been > >> achieved? I'm hitting the same problem and have some time to work on a > >> fix. > > > > Generally, it looks like del_gendisk should thaw writeback threads, but not > > during suspend, only during resume. > > Thawing the writeback thread only during resume does fix the case > Maxim originally presented: > > 0. build kernel with CONFIG_MMC_UNSAFE_RESUME > 1. insert SD card > 2. suspend > 3. remove SD card while suspended > 4. resume from suspend hangs > > But if CONFIG_MMC_UNSAFE_RESUME is not set, the kernel oopses during > suspend because the MMC device suspend times out: > > mmc0: card e624 removed > **** DPM device timeout: pxa2xx-mci.0 (pxa2xx-mci) > kernel BUG at /home/mreimer/sdg/android/android-2.1/kernel/drivers/base/power/main.c:453! > Unable to handle kernel NULL pointer dereference at virtual address 00000000 > pgd = c0004000 > [00000000] *pgd=00000000 > Internal error: Oops: 817 [#1] PREEMPT > > If I thaw the writeback thread unconditionally in del_gendisk() then > suspend and resume work as expected for both CONFIG_MMC_UNSAFE_RESUME > set/not set, even when the card is removed while suspended. > > So what is the proper fix? I don't see any reason not to let del_gendisk thaw the writeback thread during suspend. Since the device is going away anyhow, letting the thread run shouldn't cause any problems. Alan Stern _______________________________________________ linux-pm mailing list linux-pm@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linux-foundation.org/mailman/listinfo/linux-pm
