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Message-ID: <CAHrpEqQNvAxUhsU89P2ArAZiNxLMqTkf5ez+8RZPqkfSx9FRiA@mail.gmail.com>
Date: Tue, 2 Mar 2021 12:39:23 -0600
From: Zhi Li <lznuaa@...il.com>
To: Adrian Hunter <adrian.hunter@...el.com>
Cc: riteshh@...eaurora.org, asutoshd@...eaurora.org,
Ulf Hansson <ulf.hansson@...aro.org>,
linux-mmc@...r.kernel.org,
kernel list <linux-kernel@...r.kernel.org>, haibo.chen@....com
Subject: Re: [PATCH 1/1] mmc: cqhci: fix random crash when remove mmc module
On Tue, Mar 2, 2021 at 10:25 AM Adrian Hunter <adrian.hunter@...el.com> wrote:
>
> On 2/03/21 5:12 pm, Zhi Li wrote:
> >
> >
> > On Tue, Mar 2, 2021 at 1:03 AM Adrian Hunter <adrian.hunter@...el.com <mailto:adrian.hunter@...el.com>> wrote:
> >
> > On 1/03/21 7:21 pm, Frank Li wrote:
> > > [ 6684.493350] Unable to handle kernel paging request at virtual address ffff800011c5b0f0
> > > [ 6684.498531] mmc0: card 0001 removed
> > > [ 6684.501556] Mem abort info:
> > > [ 6684.509681] ESR = 0x96000047
> > > [ 6684.512786] EC = 0x25: DABT (current EL), IL = 32 bits
> > > [ 6684.518394] SET = 0, FnV = 0
> > > [ 6684.521707] EA = 0, S1PTW = 0
> > > [ 6684.524998] Data abort info:
> > > [ 6684.528236] ISV = 0, ISS = 0x00000047
> > > [ 6684.532986] CM = 0, WnR = 1
> > > [ 6684.536129] swapper pgtable: 4k pages, 48-bit VAs, pgdp=0000000081b22000
> > > [ 6684.543923] [ffff800011c5b0f0] pgd=00000000bffff003, p4d=00000000bffff003, pud=00000000bfffe003, pmd=00000000900e1003, pte=0000000000000000
> > > [ 6684.557915] Internal error: Oops: 96000047 [#1] PREEMPT SMP
> > > [ 6684.564240] Modules linked in: sdhci_esdhc_imx(-) sdhci_pltfm sdhci cqhci mmc_block mmc_core fsl_jr_uio caam_jr caamkeyblob_desc caamhash_desc caamalg_desc crypto_engine rng_core authenc libdes crct10dif_ce flexcan can_dev caam error [last unloaded: mmc_core]
> > > [ 6684.587281] CPU: 0 PID: 79138 Comm: kworker/0:3H Not tainted 5.10.9-01410-g3ba33182767b-dirty #10
> > > [ 6684.596160] Hardware name: Freescale i.MX8DXL EVK (DT)
> > > [ 6684.601320] Workqueue: kblockd blk_mq_run_work_fn
> > >
> > > [ 6684.606094] pstate: 40000005 (nZcv daif -PAN -UAO -TCO BTYPE=--)
> > > [ 6684.612286] pc : cqhci_request+0x148/0x4e8 [cqhci]
> > > ^GMessage from syslogd@ at Thu Jan 1 01:51:24 1970 ...[ 6684.617085] lr : cqhci_request+0x314/0x4e8 [cqhci]
> > > [ 6684.626734] sp : ffff80001243b9f0
> > > [ 6684.630049] x29: ffff80001243b9f0 x28: ffff00002c3dd000
> > > [ 6684.635367] x27: 0000000000000001 x26: 0000000000000001
> > > [ 6684.640690] x25: ffff00002c451000 x24: 000000000000000f
> > > [ 6684.646007] x23: ffff000017e71c80 x22: ffff00002c451000
> > > [ 6684.651326] x21: ffff00002c0f3550 x20: ffff00002c0f3550
> > > [ 6684.656651] x19: ffff000017d46880 x18: ffff00002cea1500
> > > [ 6684.661977] x17: 0000000000000000 x16: 0000000000000000
> > > [ 6684.667294] x15: 000001ee628e3ed1 x14: 0000000000000278
> > > [ 6684.672610] x13: 0000000000000001 x12: 0000000000000001
> > > [ 6684.677927] x11: 0000000000000000 x10: 0000000000000000
> > > [ 6684.683243] x9 : 000000000000002b x8 : 0000000000001000
> > > [ 6684.688560] x7 : 0000000000000010 x6 : ffff00002c0f3678
> > > [ 6684.693886] x5 : 000000000000000f x4 : ffff800011c5b000
> > > [ 6684.699211] x3 : 000000000002d988 x2 : 0000000000000008
> > > [ 6684.704537] x1 : 00000000000000f0 x0 : 0002d9880008102f
> > > [ 6684.709854] Call trace:
> > > [ 6684.712313] cqhci_request+0x148/0x4e8 [cqhci]
> > > [ 6684.716803] mmc_cqe_start_req+0x58/0x68 [mmc_core]
> > > [ 6684.721698] mmc_blk_mq_issue_rq+0x460/0x810 [mmc_block]
> > > [ 6684.727018] mmc_mq_queue_rq+0x118/0x2b0 [mmc_block]
> > >
> > > cqhci_request was called after cqhci_disable.
> > >
> > > cqhci_disable cqhci_request
> > > { {
> > > dmam_free_coherent(); (1) free
> > > if(!cq_host->enable)
> > > return
> > > (2) pass check here
> > > cq_host->enable = false;
> > >
> > > task_desc= get_desc(cq_host,tag);
> > > ^^^^ crash here
> > > (3) access memory which is already free
> > >
> > > } }
> > >
> > > Signed-off-by: Frank Li <Frank.Li@....com <mailto:Frank.Li@....com>>
> > > ---
> > > drivers/mmc/host/cqhci-core.c | 18 ++++++++++++++----
> > > 1 file changed, 14 insertions(+), 4 deletions(-)
> > >
> > > diff --git a/drivers/mmc/host/cqhci-core.c b/drivers/mmc/host/cqhci-core.c
> > > index 93b0432bb601..36d292261e50 100644
> > > --- a/drivers/mmc/host/cqhci-core.c
> > > +++ b/drivers/mmc/host/cqhci-core.c
> > > @@ -389,6 +389,7 @@ static void cqhci_off(struct mmc_host *mmc)
> > > static void cqhci_disable(struct mmc_host *mmc)
> > > {
> > > struct cqhci_host *cq_host = mmc->cqe_private;
> > > + unsigned long flags;
> > >
> > > if (!cq_host->enabled)
> > > return;
> > > @@ -397,6 +398,11 @@ static void cqhci_disable(struct mmc_host *mmc)
> > >
> > > __cqhci_disable(cq_host);
> > >
> > > + /* need wait for cqhci_request finish before free memory */
> > > + spin_lock_irqsave(&cq_host->lock, flags);
> > > + cq_host->enabled = false;
> > > + spin_unlock_irqrestore(&cq_host->lock, flags);
> > > +
> > > dmam_free_coherent(mmc_dev(mmc), cq_host->data_size,
> > > cq_host->trans_desc_base,
> > > cq_host->trans_desc_dma_base);
> > > @@ -408,7 +414,6 @@ static void cqhci_disable(struct mmc_host *mmc)
> > > cq_host->trans_desc_base = NULL;
> > > cq_host->desc_base = NULL;
> > >
> > > - cq_host->enabled = false;
> > > }
> > >
> > > static void cqhci_prep_task_desc(struct mmc_request *mrq,
> > > @@ -612,6 +617,13 @@ static int cqhci_request(struct mmc_host *mmc, struct mmc_request *mrq)
> > > cq_host->ops->enable(mmc);
> > > }
> > >
> > > + spin_lock_irqsave(&cq_host->lock, flags);
> > > + if (!cq_host->enabled) {
> > > + pr_err("%s: cqhci: not enabled\n", mmc_hostname(mmc));
> > > + err = -EINVAL;
> > > + goto out_unlock;
> > > + }
> > > +
> > > if (mrq->data) {
> > > cqhci_prep_task_desc(mrq, cq_host, tag);
> > >
> > > @@ -619,14 +631,12 @@ static int cqhci_request(struct mmc_host *mmc, struct mmc_request *mrq)
> > > if (err) {
> > > pr_err("%s: cqhci: failed to setup tx desc: %d\n",
> > > mmc_hostname(mmc), err);
> > > - return err;
> > > + goto out_unlock;
> > > }
> > > } else {
> > > cqhci_prep_dcmd_desc(mmc, mrq);
> > > }
> > >
> > > - spin_lock_irqsave(&cq_host->lock, flags);
> > > -
> > > if (cq_host->recovery_halt) {
> > > err = -EBUSY;
> > > goto out_unlock;
> > >
> >
> > Please try the following instead:
> >
> >
> > diff --git a/drivers/mmc/core/bus.c b/drivers/mmc/core/bus.c
> > index c2e70b757dd1..dfc8d2877115 100644
> > --- a/drivers/mmc/core/bus.c
> > +++ b/drivers/mmc/core/bus.c
> > @@ -399,11 +399,6 @@ void mmc_remove_card(struct mmc_card *card)
> > mmc_remove_card_debugfs(card);
> > #endif
> >
> > - if (host->cqe_enabled) {
> > - host->cqe_ops->cqe_disable(host);
> > - host->cqe_enabled = false;
> > - }
> > -
> > if (mmc_card_present(card)) {
> > if (mmc_host_is_spi(card->host)) {
> > pr_info("%s: SPI card removed\n",
> > @@ -416,6 +411,11 @@ void mmc_remove_card(struct mmc_card *card)
> > of_node_put(card->dev.of_node);
> > }
> >
> > + if (host->cqe_enabled) {
> > + host->cqe_ops->cqe_disable(host);
> > + host->cqe_enabled = false;
> > + }
> > +
> > put_device(&card->dev);
> > }
> >
> >
> > Actually this is my first solution, it can't resolve issues 100% and just reduce possibility.
> >
> > One core run The another core run
> > mmc_remove_card mmc_mq_queue_rq
> > { {
> >
> > if (mmc_card_removed(mq->card)) {
> > req->rq_flags |= RQF_QUIET;
> > return BLK_STS_IOERR;
> > }
> > //pass check here
> > device_del(&card->dev);
>
> Deleting the card device removes it from the block driver
> (i.e. mmc_blk_remove()), which cleans up the request queues,
> so the scenario you describe here should never happen.
>
> Can you determine if mmc_blk_remove() is called and whether
> it cleans up blk queues?
>
yes, mmc_blk_remove is called.
Let me run my test case. It takes at least 24 hours.
>
>
> > //free resource here
> > host->cqe_ops->cqe_disable(host);
> >
> > call cqhci_request
> > //kernel dump here to access memory that is already free.
> >
> > } }
> >
> > There is one fundamental problem that there is NOT read lock when checking mmc_card_removed, and write lock for updating md->card.
> > The risk conditions always exist between queue request and card remove.
> >
> > There are no issues for non-command queue host controllers, it just causes a redundant cmd sent by host, cmd will be timeout. Just an expected IO error
> > happened. Maybe just errors code is different.
> >
> > But Cmd queue is different, cmd queue disabled function free memory resources. if risk conditions happen, there are kernel dump.
> >
> >
> >
>
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