| Message ID | 20210930124415.1160754-1-ming.lei@redhat.com (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | [V3] scsi: core: put LLD module refcnt after SCSI device is released | expand |
Tested-by: Yi Zhang <yi.zhang@redhat.com> This patch fixed one panic issue which I found on s390x with blktests srp tests. https://lore.kernel.org/linux-block/CAHj4cs8XNtkzbbiLnFmVu82wYeQpLkVp6_wCtrnbhODay+OP9w@mail.gmail.com/#t On Thu, Sep 30, 2021 at 8:44 PM Ming Lei <ming.lei@redhat.com> wrote: > > SCSI host release is triggered when SCSI device is freed, and we have to > make sure that LLD module won't be unloaded before SCSI host instance is > released because shost->hostt is required in host release handler. > > So make sure to put LLD module refcnt after SCSI device is released. > > Fix one kernel panic of 'BUG: unable to handle page fault for address' > reported by Changhui and Yi. > > Reported-by: Changhui Zhong <czhong@redhat.com> > Reported-by: Yi Zhang <yi.zhang@redhat.com> > Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> > Signed-off-by: Ming Lei <ming.lei@redhat.com> > --- > drivers/scsi/scsi.c | 4 +++- > drivers/scsi/scsi_sysfs.c | 12 ++++++++++++ > include/scsi/scsi_device.h | 1 + > 3 files changed, 16 insertions(+), 1 deletion(-) > > diff --git a/drivers/scsi/scsi.c b/drivers/scsi/scsi.c > index b241f9e3885c..291ecc33b1fe 100644 > --- a/drivers/scsi/scsi.c > +++ b/drivers/scsi/scsi.c > @@ -553,8 +553,10 @@ EXPORT_SYMBOL(scsi_device_get); > */ > void scsi_device_put(struct scsi_device *sdev) > { > - module_put(sdev->host->hostt->module); > + struct module *mod = sdev->host->hostt->module; > + > put_device(&sdev->sdev_gendev); > + module_put(mod); > } > EXPORT_SYMBOL(scsi_device_put); > > diff --git a/drivers/scsi/scsi_sysfs.c b/drivers/scsi/scsi_sysfs.c > index 86793259e541..9ada26814011 100644 > --- a/drivers/scsi/scsi_sysfs.c > +++ b/drivers/scsi/scsi_sysfs.c > @@ -449,9 +449,16 @@ static void scsi_device_dev_release_usercontext(struct work_struct *work) > struct scsi_vpd *vpd_pg80 = NULL, *vpd_pg83 = NULL; > struct scsi_vpd *vpd_pg0 = NULL, *vpd_pg89 = NULL; > unsigned long flags; > + struct module *mod; > + bool put_mod = false; > > sdev = container_of(work, struct scsi_device, ew.work); > > + if (sdev->put_lld_mod_ref) { > + mod = sdev->host->hostt->module; > + put_mod = true; > + } > + > scsi_dh_release_device(sdev); > > parent = sdev->sdev_gendev.parent; > @@ -502,11 +509,16 @@ static void scsi_device_dev_release_usercontext(struct work_struct *work) > > if (parent) > put_device(parent); > + if (put_mod) > + module_put(mod); > } > > static void scsi_device_dev_release(struct device *dev) > { > struct scsi_device *sdp = to_scsi_device(dev); > + > + sdp->put_lld_mod_ref = try_module_get(sdp->host->hostt->module); > + > execute_in_process_context(scsi_device_dev_release_usercontext, > &sdp->ew); > } > diff --git a/include/scsi/scsi_device.h b/include/scsi/scsi_device.h > index 430b73bd02ac..54b46d590e2d 100644 > --- a/include/scsi/scsi_device.h > +++ b/include/scsi/scsi_device.h > @@ -206,6 +206,7 @@ struct scsi_device { > unsigned rpm_autosuspend:1; /* Enable runtime autosuspend at device > * creation time */ > unsigned ignore_media_change:1; /* Ignore MEDIA CHANGE on resume */ > + unsigned put_lld_mod_ref:1; /* Put LLD module ref in release */ > > bool offline_already; /* Device offline message logged */ > > -- > 2.31.1 >
On Thu, Sep 30, 2021 at 08:44:15PM +0800, Ming Lei wrote: > SCSI host release is triggered when SCSI device is freed, and we have to > make sure that LLD module won't be unloaded before SCSI host instance is > released because shost->hostt is required in host release handler. > > So make sure to put LLD module refcnt after SCSI device is released. What is a "LLD"? > Fix one kernel panic of 'BUG: unable to handle page fault for address' > reported by Changhui and Yi. > > Reported-by: Changhui Zhong <czhong@redhat.com> > Reported-by: Yi Zhang <yi.zhang@redhat.com> > Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> > Signed-off-by: Ming Lei <ming.lei@redhat.com> > --- > drivers/scsi/scsi.c | 4 +++- > drivers/scsi/scsi_sysfs.c | 12 ++++++++++++ > include/scsi/scsi_device.h | 1 + > 3 files changed, 16 insertions(+), 1 deletion(-) > > diff --git a/drivers/scsi/scsi.c b/drivers/scsi/scsi.c > index b241f9e3885c..291ecc33b1fe 100644 > --- a/drivers/scsi/scsi.c > +++ b/drivers/scsi/scsi.c > @@ -553,8 +553,10 @@ EXPORT_SYMBOL(scsi_device_get); > */ > void scsi_device_put(struct scsi_device *sdev) > { > - module_put(sdev->host->hostt->module); > + struct module *mod = sdev->host->hostt->module; > + > put_device(&sdev->sdev_gendev); > + module_put(mod); > } > EXPORT_SYMBOL(scsi_device_put); > > diff --git a/drivers/scsi/scsi_sysfs.c b/drivers/scsi/scsi_sysfs.c > index 86793259e541..9ada26814011 100644 > --- a/drivers/scsi/scsi_sysfs.c > +++ b/drivers/scsi/scsi_sysfs.c > @@ -449,9 +449,16 @@ static void scsi_device_dev_release_usercontext(struct work_struct *work) > struct scsi_vpd *vpd_pg80 = NULL, *vpd_pg83 = NULL; > struct scsi_vpd *vpd_pg0 = NULL, *vpd_pg89 = NULL; > unsigned long flags; > + struct module *mod; > + bool put_mod = false; > > sdev = container_of(work, struct scsi_device, ew.work); > > + if (sdev->put_lld_mod_ref) { Why do you need this flag at all? Shouldn't you just always grab/release the module? Why would you not want to? thanks, greg k-h
On Tue, Oct 05, 2021 at 03:35:40PM +0200, Greg Kroah-Hartman wrote: > On Thu, Sep 30, 2021 at 08:44:15PM +0800, Ming Lei wrote: > > SCSI host release is triggered when SCSI device is freed, and we have to > > make sure that LLD module won't be unloaded before SCSI host instance is > > released because shost->hostt is required in host release handler. > > > > So make sure to put LLD module refcnt after SCSI device is released. > > What is a "LLD"? Lower level driver, which is used often as one scsi term. > > > Fix one kernel panic of 'BUG: unable to handle page fault for address' > > reported by Changhui and Yi. > > > > Reported-by: Changhui Zhong <czhong@redhat.com> > > Reported-by: Yi Zhang <yi.zhang@redhat.com> > > Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> > > Signed-off-by: Ming Lei <ming.lei@redhat.com> > > --- > > drivers/scsi/scsi.c | 4 +++- > > drivers/scsi/scsi_sysfs.c | 12 ++++++++++++ > > include/scsi/scsi_device.h | 1 + > > 3 files changed, 16 insertions(+), 1 deletion(-) > > > > diff --git a/drivers/scsi/scsi.c b/drivers/scsi/scsi.c > > index b241f9e3885c..291ecc33b1fe 100644 > > --- a/drivers/scsi/scsi.c > > +++ b/drivers/scsi/scsi.c > > @@ -553,8 +553,10 @@ EXPORT_SYMBOL(scsi_device_get); > > */ > > void scsi_device_put(struct scsi_device *sdev) > > { > > - module_put(sdev->host->hostt->module); > > + struct module *mod = sdev->host->hostt->module; > > + > > put_device(&sdev->sdev_gendev); > > + module_put(mod); > > } > > EXPORT_SYMBOL(scsi_device_put); > > > > diff --git a/drivers/scsi/scsi_sysfs.c b/drivers/scsi/scsi_sysfs.c > > index 86793259e541..9ada26814011 100644 > > --- a/drivers/scsi/scsi_sysfs.c > > +++ b/drivers/scsi/scsi_sysfs.c > > @@ -449,9 +449,16 @@ static void scsi_device_dev_release_usercontext(struct work_struct *work) > > struct scsi_vpd *vpd_pg80 = NULL, *vpd_pg83 = NULL; > > struct scsi_vpd *vpd_pg0 = NULL, *vpd_pg89 = NULL; > > unsigned long flags; > > + struct module *mod; > > + bool put_mod = false; > > > > sdev = container_of(work, struct scsi_device, ew.work); > > > > + if (sdev->put_lld_mod_ref) { > > Why do you need this flag at all? > > Shouldn't you just always grab/release the module? Why would you not > want to? try_module_get() may fail in scsi_device_dev_release() in case that unloading is started, then we don't need to put it in scsi_device_dev_release_usercontext(), so this flag is required. thanks, Ming
On Thu, Oct 07, 2021 at 03:12:52PM +0800, Ming Lei wrote: > On Tue, Oct 05, 2021 at 03:35:40PM +0200, Greg Kroah-Hartman wrote: > > On Thu, Sep 30, 2021 at 08:44:15PM +0800, Ming Lei wrote: > > > SCSI host release is triggered when SCSI device is freed, and we have to > > > make sure that LLD module won't be unloaded before SCSI host instance is > > > released because shost->hostt is required in host release handler. > > > > > > So make sure to put LLD module refcnt after SCSI device is released. > > > > What is a "LLD"? > > Lower level driver, which is used often as one scsi term. > > > > > > Fix one kernel panic of 'BUG: unable to handle page fault for address' > > > reported by Changhui and Yi. > > > > > > Reported-by: Changhui Zhong <czhong@redhat.com> > > > Reported-by: Yi Zhang <yi.zhang@redhat.com> > > > Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> > > > Signed-off-by: Ming Lei <ming.lei@redhat.com> > > > --- > > > drivers/scsi/scsi.c | 4 +++- > > > drivers/scsi/scsi_sysfs.c | 12 ++++++++++++ > > > include/scsi/scsi_device.h | 1 + > > > 3 files changed, 16 insertions(+), 1 deletion(-) > > > > > > diff --git a/drivers/scsi/scsi.c b/drivers/scsi/scsi.c > > > index b241f9e3885c..291ecc33b1fe 100644 > > > --- a/drivers/scsi/scsi.c > > > +++ b/drivers/scsi/scsi.c > > > @@ -553,8 +553,10 @@ EXPORT_SYMBOL(scsi_device_get); > > > */ > > > void scsi_device_put(struct scsi_device *sdev) > > > { > > > - module_put(sdev->host->hostt->module); > > > + struct module *mod = sdev->host->hostt->module; > > > + > > > put_device(&sdev->sdev_gendev); > > > + module_put(mod); > > > } > > > EXPORT_SYMBOL(scsi_device_put); > > > > > > diff --git a/drivers/scsi/scsi_sysfs.c b/drivers/scsi/scsi_sysfs.c > > > index 86793259e541..9ada26814011 100644 > > > --- a/drivers/scsi/scsi_sysfs.c > > > +++ b/drivers/scsi/scsi_sysfs.c > > > @@ -449,9 +449,16 @@ static void scsi_device_dev_release_usercontext(struct work_struct *work) > > > struct scsi_vpd *vpd_pg80 = NULL, *vpd_pg83 = NULL; > > > struct scsi_vpd *vpd_pg0 = NULL, *vpd_pg89 = NULL; > > > unsigned long flags; > > > + struct module *mod; > > > + bool put_mod = false; > > > > > > sdev = container_of(work, struct scsi_device, ew.work); > > > > > > + if (sdev->put_lld_mod_ref) { > > > > Why do you need this flag at all? > > > > Shouldn't you just always grab/release the module? Why would you not > > want to? > > try_module_get() may fail in scsi_device_dev_release() in case that > unloading is started, then we don't need to put it in > scsi_device_dev_release_usercontext(), so this flag is required. If grabing the module reference failed then you CAN NOT call into it so you have a problem here that you seem to be papering over. Just set the module pointer to NULL and then you don't need to test it when calling module_put, right? thanks, greg k-h
On Thu, Oct 07, 2021 at 09:19:25AM +0200, Greg Kroah-Hartman wrote: > On Thu, Oct 07, 2021 at 03:12:52PM +0800, Ming Lei wrote: > > On Tue, Oct 05, 2021 at 03:35:40PM +0200, Greg Kroah-Hartman wrote: > > > On Thu, Sep 30, 2021 at 08:44:15PM +0800, Ming Lei wrote: > > > > SCSI host release is triggered when SCSI device is freed, and we have to > > > > make sure that LLD module won't be unloaded before SCSI host instance is > > > > released because shost->hostt is required in host release handler. > > > > > > > > So make sure to put LLD module refcnt after SCSI device is released. > > > > > > What is a "LLD"? > > > > Lower level driver, which is used often as one scsi term. > > > > > > > > > Fix one kernel panic of 'BUG: unable to handle page fault for address' > > > > reported by Changhui and Yi. > > > > > > > > Reported-by: Changhui Zhong <czhong@redhat.com> > > > > Reported-by: Yi Zhang <yi.zhang@redhat.com> > > > > Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> > > > > Signed-off-by: Ming Lei <ming.lei@redhat.com> > > > > --- > > > > drivers/scsi/scsi.c | 4 +++- > > > > drivers/scsi/scsi_sysfs.c | 12 ++++++++++++ > > > > include/scsi/scsi_device.h | 1 + > > > > 3 files changed, 16 insertions(+), 1 deletion(-) > > > > > > > > diff --git a/drivers/scsi/scsi.c b/drivers/scsi/scsi.c > > > > index b241f9e3885c..291ecc33b1fe 100644 > > > > --- a/drivers/scsi/scsi.c > > > > +++ b/drivers/scsi/scsi.c > > > > @@ -553,8 +553,10 @@ EXPORT_SYMBOL(scsi_device_get); > > > > */ > > > > void scsi_device_put(struct scsi_device *sdev) > > > > { > > > > - module_put(sdev->host->hostt->module); > > > > + struct module *mod = sdev->host->hostt->module; > > > > + > > > > put_device(&sdev->sdev_gendev); > > > > + module_put(mod); > > > > } > > > > EXPORT_SYMBOL(scsi_device_put); > > > > > > > > diff --git a/drivers/scsi/scsi_sysfs.c b/drivers/scsi/scsi_sysfs.c > > > > index 86793259e541..9ada26814011 100644 > > > > --- a/drivers/scsi/scsi_sysfs.c > > > > +++ b/drivers/scsi/scsi_sysfs.c > > > > @@ -449,9 +449,16 @@ static void scsi_device_dev_release_usercontext(struct work_struct *work) > > > > struct scsi_vpd *vpd_pg80 = NULL, *vpd_pg83 = NULL; > > > > struct scsi_vpd *vpd_pg0 = NULL, *vpd_pg89 = NULL; > > > > unsigned long flags; > > > > + struct module *mod; > > > > + bool put_mod = false; > > > > > > > > sdev = container_of(work, struct scsi_device, ew.work); > > > > > > > > + if (sdev->put_lld_mod_ref) { > > > > > > Why do you need this flag at all? > > > > > > Shouldn't you just always grab/release the module? Why would you not > > > want to? > > > > try_module_get() may fail in scsi_device_dev_release() in case that > > unloading is started, then we don't need to put it in > > scsi_device_dev_release_usercontext(), so this flag is required. > > If grabing the module reference failed then you CAN NOT call into it so > you have a problem here that you seem to be papering over. Just set the > module pointer to NULL and then you don't need to test it when calling > module_put, right? OK, sounds good, given the failure means that we shouldn't touch it any more. Thanks, Ming
diff --git a/drivers/scsi/scsi.c b/drivers/scsi/scsi.c index b241f9e3885c..291ecc33b1fe 100644 --- a/drivers/scsi/scsi.c +++ b/drivers/scsi/scsi.c @@ -553,8 +553,10 @@ EXPORT_SYMBOL(scsi_device_get); */ void scsi_device_put(struct scsi_device *sdev) { - module_put(sdev->host->hostt->module); + struct module *mod = sdev->host->hostt->module; + put_device(&sdev->sdev_gendev); + module_put(mod); } EXPORT_SYMBOL(scsi_device_put); diff --git a/drivers/scsi/scsi_sysfs.c b/drivers/scsi/scsi_sysfs.c index 86793259e541..9ada26814011 100644 --- a/drivers/scsi/scsi_sysfs.c +++ b/drivers/scsi/scsi_sysfs.c @@ -449,9 +449,16 @@ static void scsi_device_dev_release_usercontext(struct work_struct *work) struct scsi_vpd *vpd_pg80 = NULL, *vpd_pg83 = NULL; struct scsi_vpd *vpd_pg0 = NULL, *vpd_pg89 = NULL; unsigned long flags; + struct module *mod; + bool put_mod = false; sdev = container_of(work, struct scsi_device, ew.work); + if (sdev->put_lld_mod_ref) { + mod = sdev->host->hostt->module; + put_mod = true; + } + scsi_dh_release_device(sdev); parent = sdev->sdev_gendev.parent; @@ -502,11 +509,16 @@ static void scsi_device_dev_release_usercontext(struct work_struct *work) if (parent) put_device(parent); + if (put_mod) + module_put(mod); } static void scsi_device_dev_release(struct device *dev) { struct scsi_device *sdp = to_scsi_device(dev); + + sdp->put_lld_mod_ref = try_module_get(sdp->host->hostt->module); + execute_in_process_context(scsi_device_dev_release_usercontext, &sdp->ew); } diff --git a/include/scsi/scsi_device.h b/include/scsi/scsi_device.h index 430b73bd02ac..54b46d590e2d 100644 --- a/include/scsi/scsi_device.h +++ b/include/scsi/scsi_device.h @@ -206,6 +206,7 @@ struct scsi_device { unsigned rpm_autosuspend:1; /* Enable runtime autosuspend at device * creation time */ unsigned ignore_media_change:1; /* Ignore MEDIA CHANGE on resume */ + unsigned put_lld_mod_ref:1; /* Put LLD module ref in release */ bool offline_already; /* Device offline message logged */
SCSI host release is triggered when SCSI device is freed, and we have to make sure that LLD module won't be unloaded before SCSI host instance is released because shost->hostt is required in host release handler. So make sure to put LLD module refcnt after SCSI device is released. Fix one kernel panic of 'BUG: unable to handle page fault for address' reported by Changhui and Yi. Reported-by: Changhui Zhong <czhong@redhat.com> Reported-by: Yi Zhang <yi.zhang@redhat.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Ming Lei <ming.lei@redhat.com> --- drivers/scsi/scsi.c | 4 +++- drivers/scsi/scsi_sysfs.c | 12 ++++++++++++ include/scsi/scsi_device.h | 1 + 3 files changed, 16 insertions(+), 1 deletion(-)