From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Rafael J. Wysocki" Subject: Re: [PATCH -mmotm] fbmem: fix fb_info->lock and mm->mmap_sem circular locking dependency Date: Sun, 22 Mar 2009 18:57:19 +0100 Message-ID: <200903221857.20473.rjw@sisk.pl> References: <498817E2.3020008@gmail.com> <1233783983-28802-1-git-send-email-righi.andrea@gmail.com> <200903221748.42871.arvidjaar@gmail.com> Mime-Version: 1.0 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: In-Reply-To: <200903221748.42871.arvidjaar@gmail.com> Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org List-ID: Content-Type: text/plain; charset="utf-8" To: Andrey Borzenkov Cc: Andrea Righi , Andrew Morton , Geert Uytterhoeven , "Antonino A. Daplas" , linux-fbdev-devel@lists.sourceforge.net, linux-pm@lists.linux-foundation.org, linux-kernel@vger.kernel.org, Dave Jones , Harvey Harrison , Johannes Weiner , Stefan Richter On Sunday 22 March 2009, Andrey Borzenkov wrote: > On 5 =D1=84=D0=B5=D0=B2=D1=80=D0=B0=D0=BB=D1=8F 2009 00:46:23 Andrea = Righi wrote: > > Fix this circular locking dependencies in the frame buffer console > > driver pushing down the mutex fb_info->lock. > > > > Circular locking dependecies occur calling the blocking > > fb_notifier_call_chain() with fb_info->lock held. Notifier callback= s > > can try to acquire mm->mmap_sem, while fb_mmap() acquires the locks > > in the reverse order mm->mmap_sem =3D> fb_info->lock. > > > > Tested-by: Andrey Borzenkov > > Signed-off-by: Andrea Righi >=20 > Hmm ... is it in current Linus tree? Because I happened to have this = again=20 > in rc8: It doesn't seems so, at least I don't see it in there. Thanks, Rafael > [47800.440873] =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D > [47800.440950] [ INFO: possible circular locking dependency detected = ] > [47800.440981] 2.6.29-rc8-1avb #35 > [47800.440999] ------------------------------------------------------= - > [47800.441026] s2disk/19740 is trying to acquire lock: > [47800.441057] (&fb_info->lock){--..}, at: [] fb_mmap+0x97= /0x170 > [47800.441149]=20 > [47800.441152] but task is already holding lock: > [47800.441183] (&mm->mmap_sem){----}, at: [] sys_mmap2+0x8= e/0xc0 > [47800.441260]=20 > [47800.441262] which lock already depends on the new lock. > [47800.441266]=20 > [47800.441307]=20 > [47800.441309] the existing dependency chain (in reverse order) is: > [47800.441345]=20 > [47800.441347] -> #3 (&mm->mmap_sem){----}: > [47800.441426] [] __lock_acquire+0x129f/0x1930 > [47800.441466] [] lock_acquire+0x5c/0x80 > [47800.441500] [] might_fault+0x77/0xa0 > [47800.441548] [] copy_to_user+0x36/0x120 > [47800.441591] [] filldir+0x97/0xe0 > [47800.441627] [] sysfs_readdir+0x129/0x220 > [47800.441668] [] vfs_readdir+0x86/0xa0 > [47800.441701] [] sys_getdents+0x68/0xc0 > [47800.441734] [] syscall_call+0x7/0xb > [47800.441770] [] 0xffffffff > [47800.441839]=20 > [47800.441842] -> #2 (sysfs_mutex){--..}: > [47800.441906] [] __lock_acquire+0x129f/0x1930 > [47800.441941] [] lock_acquire+0x5c/0x80 > [47800.441974] [] mutex_lock_nested+0xba/0x2f0 > [47800.442012] [] sysfs_addrm_start+0x2c/0xc0 > [47800.442012] [] create_dir+0x40/0x90 > [47800.442012] [] sysfs_create_dir+0x2b/0x50 > [47800.442012] [] kobject_add_internal+0xbc/0x1b0 > [47800.442012] [] kobject_add_varg+0x31/0x50 > [47800.442012] [] kobject_add+0x2c/0x60 > [47800.442012] [] device_add+0xa8/0x550 > [47800.442012] [] device_register+0x12/0x20 > [47800.442012] [] device_create_vargs+0xab/0xc0 > [47800.442012] [] device_create+0x28/0x30 > [47800.442012] [] register_con_driver+0xed/0x130 > [47800.442012] [] take_over_console+0x1b/0x50 > [47800.442012] [] fbcon_takeover+0x5d/0xb0 > [47800.442012] [] fbcon_event_notify+0x820/0x900 > [47800.442012] [] notifier_call_chain+0x53/0xa0 > [47800.442012] [] __blocking_notifier_call_chain+0x4= 4/0x60 > [47800.442012] [] blocking_notifier_call_chain+0x1a/= 0x20 > [47800.442012] [] fb_notifier_call_chain+0x11/0x20 > [47800.442012] [] register_framebuffer+0x168/0x220 > [47800.442012] [] vesafb_probe+0x542/0x783 > [47800.442012] [] platform_drv_probe+0xf/0x20 > [47800.442012] [] driver_probe_device+0x87/0x1b0 > [47800.442012] [] __device_attach+0x8/0x10 > [47800.442012] [] bus_for_each_drv+0x5b/0x80 > [47800.442012] [] device_attach+0x76/0x80 > [47800.442012] [] bus_attach_device+0x47/0x70 > [47800.442012] [] device_add+0x323/0x550 > [47800.442012] [] platform_device_add+0x175/0x1c0 > [47800.442012] [] vesafb_init+0x9a/0x1ec > [47800.442012] [] do_one_initcall+0x2a/0x160 > [47800.442012] [] kernel_init+0x83/0xd5 > [47800.442012] [] kernel_thread_helper+0x7/0x10 > [47800.442012] [] 0xffffffff > [47800.442012]=20 > [47800.442012] -> #1 ((fb_notifier_list).rwsem){----}: > [47800.442012] [] __lock_acquire+0x129f/0x1930 > [47800.442012] [] lock_acquire+0x5c/0x80 > [47800.442012] [] down_read+0x49/0x90 > [47800.442012] [] __blocking_notifier_call_chain+0x2= a/0x60 > [47800.442012] [] blocking_notifier_call_chain+0x1a/= 0x20 > [47800.442012] [] fb_notifier_call_chain+0x11/0x20 > [47800.442012] [] do_fb_ioctl+0x2ae/0x5d0 > [47800.442012] [] fb_ioctl+0x1d/0x20 > [47800.442012] [] vfs_ioctl+0x20/0x80 > [47800.442012] [] do_vfs_ioctl+0x72/0x570 > [47800.442012] [] sys_ioctl+0x39/0x70 > [47800.442012] [] sysenter_do_call+0x12/0x31 > [47800.442012] [] 0xffffffff > [47800.442012]=20 > [47800.442012] -> #0 (&fb_info->lock){--..}: > [47800.442012] [] __lock_acquire+0x140c/0x1930 > [47800.442012] [] lock_acquire+0x5c/0x80 > [47800.442012] [] mutex_lock_nested+0xba/0x2f0 > [47800.442012] [] fb_mmap+0x97/0x170 > [47800.442012] [] mmap_region+0x2e0/0x440 > [47800.442012] [] do_mmap_pgoff+0x1ca/0x2f0 > [47800.442012] [] sys_mmap2+0xad/0xc0 > [47800.442012] [] sysenter_do_call+0x12/0x31 > [47800.442012] [] 0xffffffff > [47800.442012]=20 > [47800.442012] other info that might help us debug this: > [47800.442012]=20 > [47800.442012] 1 lock held by s2disk/19740: > [47800.442012] #0: (&mm->mmap_sem){----}, at: []=20 > sys_mmap2+0x8e/0xc0 > [47800.442012]=20 > [47800.442012] stack backtrace: > [47800.442012] Pid: 19740, comm: s2disk Not tainted 2.6.29-rc8-1avb #= 35 > [47800.442012] Call Trace: > [47800.442012] [] ? printk+0x18/0x1c > [47800.442012] [] print_circular_bug_tail+0xcf/0xe0 > [47800.442012] [] __lock_acquire+0x140c/0x1930 > [47800.442012] [] ? add_wait_queue+0x36/0x50 > [47800.442012] [] ? lock_release_holdtime+0x35/0x210 > [47800.442012] [] lock_acquire+0x5c/0x80 > [47800.442012] [] ? fb_mmap+0x97/0x170 > [47800.442012] [] mutex_lock_nested+0xba/0x2f0 > [47800.442012] [] ? fb_mmap+0x97/0x170 > [47800.442012] [] ? fb_mmap+0x97/0x170 > [47800.442012] [] ? kmem_cache_alloc+0xa5/0x100 > [47800.442012] [] fb_mmap+0x97/0x170 > [47800.442012] [] mmap_region+0x2e0/0x440 > [47800.442012] [] do_mmap_pgoff+0x1ca/0x2f0 > [47800.442012] [] sys_mmap2+0xad/0xc0 > [47800.442012] [] sysenter_do_call+0x12/0x31 > [47803.041426] Syncing filesystems ... done. > [47803.055587] Freezing user space processes ... (elapsed 0.00 second= s)=20 > done. > [47803.059328] Freezing remaining freezable tasks ... (elapsed 0.00 s= econds)=20 > done. >=20 >=20 > > --- > > drivers/video/backlight/backlight.c | 3 + > > drivers/video/backlight/lcd.c | 3 + > > drivers/video/console/fbcon.c | 73 > > ++++++++++++++++++++++++++++++----- drivers/video/fbmem.c = =20 > > | 11 +----- > > 4 files changed, 70 insertions(+), 20 deletions(-) > > > > diff --git a/drivers/video/backlight/backlight.c > > b/drivers/video/backlight/backlight.c index 157057c..dd37cbc 100644 > > --- a/drivers/video/backlight/backlight.c > > +++ b/drivers/video/backlight/backlight.c > > @@ -35,6 +35,8 @@ static int fb_notifier_callback(struct > > notifier_block *self, return 0; > > > > bd =3D container_of(self, struct backlight_device, fb_notif); > > + if (!lock_fb_info(evdata->info)) > > + return -ENODEV; > > mutex_lock(&bd->ops_lock); > > if (bd->ops) > > if (!bd->ops->check_fb || > > @@ -47,6 +49,7 @@ static int fb_notifier_callback(struct > > notifier_block *self, backlight_update_status(bd); > > } > > mutex_unlock(&bd->ops_lock); > > + unlock_fb_info(evdata->info); > > return 0; > > } > > > > diff --git a/drivers/video/backlight/lcd.c > > b/drivers/video/backlight/lcd.c index b644947..0bb13df 100644 > > --- a/drivers/video/backlight/lcd.c > > +++ b/drivers/video/backlight/lcd.c > > @@ -40,6 +40,8 @@ static int fb_notifier_callback(struct > > notifier_block *self, if (!ld->ops) > > return 0; > > > > + if (!lock_fb_info(evdata->info)) > > + return -ENODEV; > > mutex_lock(&ld->ops_lock); > > if (!ld->ops->check_fb || ld->ops->check_fb(ld, evdata->info)) { > > if (event =3D=3D FB_EVENT_BLANK) { > > @@ -51,6 +53,7 @@ static int fb_notifier_callback(struct > > notifier_block *self, } > > } > > mutex_unlock(&ld->ops_lock); > > + unlock_fb_info(evdata->info); > > return 0; > > } > > > > diff --git a/drivers/video/console/fbcon.c > > b/drivers/video/console/fbcon.c index 1657b96..2cd500a 100644 > > --- a/drivers/video/console/fbcon.c > > +++ b/drivers/video/console/fbcon.c > > @@ -2954,8 +2954,11 @@ static int fbcon_fb_unbind(int idx) > > > > static int fbcon_fb_unregistered(struct fb_info *info) > > { > > - int i, idx =3D info->node; > > + int i, idx; > > > > + if (!lock_fb_info(info)) > > + return -ENODEV; > > + idx =3D info->node; > > for (i =3D first_fb_vc; i <=3D last_fb_vc; i++) { > > if (con2fb_map[i] =3D=3D idx) > > con2fb_map[i] =3D -1; > > @@ -2979,13 +2982,14 @@ static int fbcon_fb_unregistered(struct > > fb_info *info) } > > } > > > > - if (!num_registered_fb) > > - unregister_con_driver(&fb_con); > > - > > - > > if (primary_device =3D=3D idx) > > primary_device =3D -1; > > > > + unlock_fb_info(info); > > + > > + if (!num_registered_fb) > > + unregister_con_driver(&fb_con); > > + > > return 0; > > } > > > > @@ -3021,9 +3025,13 @@ static inline void fbcon_select_primary(stru= ct > > fb_info *info) > > > > static int fbcon_fb_registered(struct fb_info *info) > > { > > - int ret =3D 0, i, idx =3D info->node; > > + int ret =3D 0, i, idx; > > > > + if (!lock_fb_info(info)) > > + return -ENODEV; > > + idx =3D info->node; > > fbcon_select_primary(info); > > + unlock_fb_info(info); > > > > if (info_idx =3D=3D -1) { > > for (i =3D first_fb_vc; i <=3D last_fb_vc; i++) { > > @@ -3124,7 +3132,7 @@ static void fbcon_get_requirement(struct > > fb_info *info, } > > } > > > > -static int fbcon_event_notify(struct notifier_block *self, > > +static int fbcon_event_notify(struct notifier_block *self, > > unsigned long action, void *data) > > { > > struct fb_event *event =3D data; > > @@ -3132,7 +3140,7 @@ static int fbcon_event_notify(struct > > notifier_block *self, struct fb_videomode *mode; > > struct fb_con2fbmap *con2fb; > > struct fb_blit_caps *caps; > > - int ret =3D 0; > > + int idx, ret =3D 0; > > > > /* > > * ignore all events except driver registration and deregistratio= n > > @@ -3144,23 +3152,54 @@ static int fbcon_event_notify(struct > > notifier_block *self, > > > > switch(action) { > > case FB_EVENT_SUSPEND: > > + if (!lock_fb_info(info)) { > > + ret =3D -ENODEV; > > + goto done; > > + } > > fbcon_suspended(info); > > + unlock_fb_info(info); > > break; > > case FB_EVENT_RESUME: > > + if (!lock_fb_info(info)) { > > + ret =3D -ENODEV; > > + goto done; > > + } > > fbcon_resumed(info); > > + unlock_fb_info(info); > > break; > > case FB_EVENT_MODE_CHANGE: > > + if (!lock_fb_info(info)) { > > + ret =3D -ENODEV; > > + goto done; > > + } > > fbcon_modechanged(info); > > + unlock_fb_info(info); > > break; > > case FB_EVENT_MODE_CHANGE_ALL: > > + if (!lock_fb_info(info)) { > > + ret =3D -ENODEV; > > + goto done; > > + } > > fbcon_set_all_vcs(info); > > + unlock_fb_info(info); > > break; > > case FB_EVENT_MODE_DELETE: > > mode =3D event->data; > > + if (!lock_fb_info(info)) { > > + ret =3D -ENODEV; > > + goto done; > > + } > > ret =3D fbcon_mode_deleted(info, mode); > > + unlock_fb_info(info); > > break; > > case FB_EVENT_FB_UNBIND: > > - ret =3D fbcon_fb_unbind(info->node); > > + if (!lock_fb_info(info)) { > > + ret =3D -ENODEV; > > + goto done; > > + } > > + idx =3D info->node; > > + unlock_fb_info(info); > > + ret =3D fbcon_fb_unbind(idx); > > break; > > case FB_EVENT_FB_REGISTERED: > > ret =3D fbcon_fb_registered(info); > > @@ -3178,17 +3217,31 @@ static int fbcon_event_notify(struct > > notifier_block *self, con2fb->framebuffer =3D > > con2fb_map[con2fb->console - 1]; > > break; > > case FB_EVENT_BLANK: > > + if (!lock_fb_info(info)) { > > + ret =3D -ENODEV; > > + goto done; > > + } > > fbcon_fb_blanked(info, *(int *)event->data); > > + unlock_fb_info(info); > > break; > > case FB_EVENT_NEW_MODELIST: > > + if (!lock_fb_info(info)) { > > + ret =3D -ENODEV; > > + goto done; > > + } > > fbcon_new_modelist(info); > > + unlock_fb_info(info); > > break; > > case FB_EVENT_GET_REQ: > > caps =3D event->data; > > + if (!lock_fb_info(info)) { > > + ret =3D -ENODEV; > > + goto done; > > + } > > fbcon_get_requirement(info, caps); > > + unlock_fb_info(info); > > break; > > } > > - > > done: > > return ret; > > } > > diff --git a/drivers/video/fbmem.c b/drivers/video/fbmem.c > > index cfd9dce..b64f061 100644 > > --- a/drivers/video/fbmem.c > > +++ b/drivers/video/fbmem.c > > @@ -1086,13 +1086,8 @@ static long do_fb_ioctl(struct fb_info *info= , > > unsigned int cmd, return -EINVAL; > > con2fb.framebuffer =3D -1; > > event.data =3D &con2fb; > > - > > - if (!lock_fb_info(info)) > > - return -ENODEV; > > event.info =3D info; > > fb_notifier_call_chain(FB_EVENT_GET_CONSOLE_MAP, &event); > > - unlock_fb_info(info); > > - > > ret =3D copy_to_user(argp, &con2fb, sizeof(con2fb)) ? -EFAULT : = 0; > > break; > > case FBIOPUT_CON2FBMAP: > > @@ -1109,12 +1104,8 @@ static long do_fb_ioctl(struct fb_info *info= , > > unsigned int cmd, break; > > } > > event.data =3D &con2fb; > > - if (!lock_fb_info(info)) > > - return -ENODEV; > > event.info =3D info; > > - ret =3D fb_notifier_call_chain(FB_EVENT_SET_CONSOLE_MAP, > > - &event); > > - unlock_fb_info(info); > > + ret =3D fb_notifier_call_chain(FB_EVENT_SET_CONSOLE_MAP, &event)= ; > > break; > > case FBIOBLANK: > > if (!lock_fb_info(info))