From: Maxim Levitsky <maximlevitsky@xxxxxxxxx>
Presently the following operations lead to a hang:
-> Have a kernel with CONFIG_MMC_UNSAFE_RESUME
-> Insert MMC/SD card
-> Suspend/hibernate the system
-> While system is hibernated/suspended pull the card off
-> Resume the system
-> Hang
[<ffffffff8106620a>] ? prepare_to_wait+0x2a/0x90
[<ffffffff810790bd>] ? trace_hardirqs_on+0xd/0x10
[<ffffffff8140db12>] ? _raw_spin_unlock_irqrestore+0x42/0x80
[<ffffffff8112a390>] ? bdi_sched_wait+0x0/0x20
[<ffffffff8112a39e>] bdi_sched_wait+0xe/0x20
[<ffffffff8140af6f>] __wait_on_bit+0x5f/0x90
[<ffffffff8112a390>] ? bdi_sched_wait+0x0/0x20
[<ffffffff8140b018>] out_of_line_wait_on_bit+0x78/0x90
[<ffffffff81065fd0>] ? wake_bit_function+0x0/0x40
[<ffffffff8112a2d3>] ? bdi_queue_work+0xa3/0xe0
[<ffffffff8112a37f>] bdi_sync_writeback+0x6f/0x80
[<ffffffff8112a3d2>] sync_inodes_sb+0x22/0x120
[<ffffffff8112f1d2>] __sync_filesystem+0x82/0x90
[<ffffffff8112f3db>] sync_filesystem+0x4b/0x70
[<ffffffff811391de>] fsync_bdev+0x2e/0x60
[<ffffffff812226be>] invalidate_partition+0x2e/0x50
[<ffffffff8116b92f>] del_gendisk+0x3f/0x140
[<ffffffffa00c0233>] mmc_blk_remove+0x33/0x60 [mmc_block]
[<ffffffff81338977>] mmc_bus_remove+0x17/0x20
[<ffffffff812ce746>] __device_release_driver+0x66/0xc0
[<ffffffff812ce89d>] device_release_driver+0x2d/0x40
[<ffffffff812cd9b5>] bus_remove_device+0xb5/0x120
[<ffffffff812cb46f>] device_del+0x12f/0x1a0
[<ffffffff81338a5b>] mmc_remove_card+0x5b/0x90
[<ffffffff8133ac27>] mmc_sd_remove+0x27/0x50
[<ffffffff81337d8c>] mmc_resume_host+0x10c/0x140
[<ffffffffa00850e9>] sdhci_resume_host+0x69/0xa0 [sdhci]
[<ffffffffa0bdc39e>] sdhci_pci_resume+0x8e/0xb0 [sdhci_pci]
because del_gendisk() tries to perform writeout when some devices are in
the suspended state.
If CONFIG_MMC_UNSAFE_RESUME is set, mmc core allows the user to
suspend/resume the card normally assuming he won't change the card or
modify it in another system. The former case is actually handled quite
well.
If CONFIG_MMC_UNSAFE_RESUME isn't set, it removes the card during suspend,
and I now think (and will test) that this will still hang the system this
time on suspend.
Fix that by removing the code that did that in mmc_resume_host. It is
possible because card detection logic will kick it later and remove the
card.
Also make mtd workqueue freezeable, so it won't attempt to add/remove the
card while userspace is frozen.
Signed-off-by: Maxim Levitsky <maximlevitsky@xxxxxxxxx>
Cc: "Rafael J. Wysocki" <rjw@xxxxxxx>
Cc: David Woodhouse <dwmw2@xxxxxxxxxxxxx>
Cc: Jorg Schummer <ext-jorg.2.schummer@xxxxxxxxx>
Cc: Nicolas Pitre <nico@xxxxxxxxxxx>
Cc: <linux-mmc@xxxxxxxxxxxxxxx>
Cc: <stable@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
drivers/mmc/core/core.c | 9 ++-------
1 file changed, 2 insertions(+), 7 deletions(-)
diff -puN drivers/mmc/core/core.c~mmc-fix-hang-if-card-was-removed-during-suspend-and-unsafe-resume-was-enabled drivers/mmc/core/core.c
--- a/drivers/mmc/core/core.c~mmc-fix-hang-if-card-was-removed-during-suspend-and-unsafe-resume-was-enabled
+++ a/drivers/mmc/core/core.c
@@ -1257,7 +1257,6 @@ int mmc_suspend_host(struct mmc_host *ho
if (host->caps & MMC_CAP_DISABLE)
cancel_delayed_work(&host->disable);
cancel_delayed_work(&host->detect);
- mmc_flush_scheduled_work();
mmc_bus_get(host);
if (host->bus_ops && !host->bus_dead) {
@@ -1300,15 +1299,11 @@ int mmc_resume_host(struct mmc_host *hos
mmc_select_voltage(host, host->ocr);
BUG_ON(!host->bus_ops->resume);
err = host->bus_ops->resume(host);
+
if (err) {
printk(KERN_WARNING "%s: error %d during resume "
"(card was removed?)\n",
mmc_hostname(host), err);
- if (host->bus_ops->remove)
- host->bus_ops->remove(host);
- mmc_claim_host(host);
- mmc_detach_bus(host);
- mmc_release_host(host);
/* no need to bother upper layers */
err = 0;
}
@@ -1332,7 +1327,7 @@ static int __init mmc_init(void)
{
int ret;
- workqueue = create_singlethread_workqueue("kmmcd");
+ workqueue = create_freezeable_workqueue("kmmcd");
if (!workqueue)
return -ENOMEM;
_
--
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