On 14 August 2014 12:29, Yunpeng Gao <yunpeng.gao@xxxxxxxxx> wrote:
> From: Chuanxiao Dong <chuanxiao.dong@xxxxxxxxx>
>
> With one special SD card, below divide by zero error observed:
> ...
> [ 2.144300] divide error: 0000 [#1] PREEMPT SMP
> [ 2.148860] Modules linked in:
> [ 2.151898]
> [ 2.152685] Set up 4031 stolen pages starting at 0x0001f000, GTT offset 0K
> [ 2.157330] Set up 0 CI stolen pages starting at 0x00000000, GTT offset 131072K
> [ 2.167581] Pid: 5, comm: kworker/u:0 Not tainted 3.0.8-138216-g974a2ab #1
> [ 2.169506] [drm] PSB GTT mem manager ready, tt_start 4031, tt_size 28737 pages
> [ 2.169906] [drm] SGX core id = 0x00000000
> [ 2.169920] [drm] SGX core rev major = 0x00, minor = 0x00
> [ 2.169934] [drm] SGX core rev maintenance = 0x00, designer = 0x00
> [ 2.197370] Intel Corporation Medfield/iCDKB
> [ 2.201716] EIP: 0060:[<c1697ca6>] EFLAGS: 00010246 CPU: 1
> [ 2.207198] EIP is at mmc_init_erase+0x76/0x150
> [ 2.211704] EAX: 00002000 EBX: dcd1b400 ECX: 00002000 EDX: 00000000
> [ 2.217957] ESI: 00000000 EDI: dcd5c800 EBP: dd867e84 ESP: dd867e7c
> [ 2.224214] DS: 007b ES: 007b FS: 00d8 GS: 0000 SS: 0068
> [ 2.229605] Process kworker/u:0 (pid: 5, ti=dd866000 task=dd868000 task.ti=dd866000)
> [ 2.237325] Stack:
> [ 2.239322] dcd1b400 00000000 dd867eb0 c16a06da c1ab7c44 dd995aa8 00000003 00000000
> [ 2.247054] 00000000 00000000 dcd5c800 00000000 dcd1b400 dd867ef8 c16a1012 c1698b00
> [ 2.254785] 00000029 00000001 c194eb80 dcd5c9ec dd867e00 c1239b00 00000000 00000000
> [ 2.262519] Call Trace:
> [ 2.264975] [<c16a06da>] mmc_sd_setup_card+0x1da/0x4f0
> [ 2.270183] [<c16a1012>] mmc_sd_init_card+0x192/0xc40
> [ 2.275304] [<c1698b00>] ? __mmc_claim_host+0x160/0x160
> [ 2.280610] [<c1239b00>] ? __schedule_bug+0x50/0x80
> [ 2.285556] [<c16a1b89>] mmc_attach_sd+0xc9/0x230
> [ 2.290333] [<c169b6ef>] mmc_rescan+0x25f/0x2c0
> [ 2.294943] [<c1274223>] process_one_work+0x103/0x400
> [ 2.300065] [<c12670fd>] ? mod_timer+0x1ad/0x3c0
> [ 2.304756] [<c169b490>] ? mmc_suspend_host+0x1a0/0x1a0
> [ 2.310056] [<c127502d>] worker_thread+0x12d/0x4a0
> [ 2.314921] [<c18fcfbd>] ? preempt_schedule+0x2d/0x50
> [ 2.320047] [<c1274f00[ 2.323976] ---[ end trace 5398ec2720494438 ]---
> ...
>
> So, seems this bad SD card does not set valid value in related SSR / CSD register fields.
> And then the driver will set card->erase_size to 0.
> Then it triggered this divided by zero error when calculate card->pref_erase.
>
> Submit this patch to fix the issue.
>
> Signed-off-by: Yunpeng Gao <yunpeng.gao@xxxxxxxxx>
> Signed-off-by: Chuanxiao Dong <chuanxiao.dong@xxxxxxxxx>
> ---
> drivers/mmc/core/core.c | 5 +++--
> 1 file changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c
> index 7dc0c85..385373db 100644
> --- a/drivers/mmc/core/core.c
> +++ b/drivers/mmc/core/core.c
> @@ -1761,7 +1761,7 @@ void mmc_init_erase(struct mmc_card *card)
> card->erase_shift = ffs(card->ssr.au) - 1;
> } else if (card->ext_csd.hc_erase_size) {
> card->pref_erase = card->ext_csd.hc_erase_size;
> - } else {
> + } else if (card->erase_size) {
> sz = (card->csd.capacity << (card->csd.read_blkbits - 9)) >> 11;
> if (sz < 128)
> card->pref_erase = 512 * 1024 / 512;
> @@ -1778,7 +1778,8 @@ void mmc_init_erase(struct mmc_card *card)
> if (sz)
> card->pref_erase += card->erase_size - sz;
> }
> - }
> + } else
> + card->pref_erase = 0;
> }
>
Overall this seems like a good idea. Though I wonder what happens with
the QUEUE_FLAG_DISCARD? I suppose we would to prevent it from being
set when initiating the blk dev queue, right?
Kind regards
Uffe
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