Revision f6619ef7508261be2ba3ded313ccc46ce670d0d3 authored by Wang, Rui Y on 18 November 2015, 15:00:53 UTC, committed by Dave Airlie on 19 November 2015, 03:20:01 UTC
The machine hang completely with the following message on the console: [ 487.777538] BUG: unable to handle kernel NULL pointer dereference at 0000000000000060 [ 487.777554] IP: [<ffffffff8158aaee>] _raw_spin_lock+0xe/0x30 [ 487.777557] PGD 42e9f7067 PUD 42f2fa067 PMD 0 [ 487.777560] Oops: 0002 [#1] SMP ... [ 487.777618] CPU: 21 PID: 3190 Comm: Xorg Tainted: G E 4.4.0-rc1-3-default+ #6 [ 487.777620] Hardware name: Intel Corporation BRICKLAND/BRICKLAND, BIOS BRHSXSD1.86B.0059.R00.1501081238 01/08/2015 [ 487.777621] task: ffff880853ae4680 ti: ffff8808696d4000 task.ti: ffff8808696d4000 [ 487.777625] RIP: 0010:[<ffffffff8158aaee>] [<ffffffff8158aaee>] _raw_spin_lock+0xe/0x30 [ 487.777627] RSP: 0018:ffff8808696d79c0 EFLAGS: 00010246 [ 487.777628] RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000 [ 487.777629] RDX: 0000000000000001 RSI: 0000000000000000 RDI: 0000000000000060 [ 487.777630] RBP: ffff8808696d79e0 R08: 0000000000000000 R09: ffff88086924a780 [ 487.777631] R10: 000000000001bb40 R11: 0000000000003246 R12: 0000000000000000 [ 487.777632] R13: ffff880463a27360 R14: ffff88046ca50218 R15: 0000000000000080 [ 487.777634] FS: 00007f3f81c5a8c0(0000) GS:ffff88086f060000(0000) knlGS:0000000000000000 [ 487.777635] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 487.777636] CR2: 0000000000000060 CR3: 000000042e678000 CR4: 00000000001406e0 [ 487.777638] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 487.777639] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 487.777639] Stack: [ 487.777642] ffffffffa00eb5fa ffff8808696d7b60 ffff88086b87d800 0000000000000000 [ 487.777644] ffff8808696d7ac8 ffffffffa01694b6 ffff8808696d7ae8 ffffffff8109c8d5 [ 487.777647] ffff880469158740 ffff880463a27000 ffff88086b87d800 ffff88086b87d800 [ 487.777647] Call Trace: [ 487.777674] [<ffffffffa00eb5fa>] ? drm_gem_object_lookup+0x1a/0xa0 [drm] [ 487.777681] [<ffffffffa01694b6>] mga_crtc_cursor_set+0xc6/0xb60 [mgag200] [ 487.777691] [<ffffffff8109c8d5>] ? find_busiest_group+0x35/0x4a0 [ 487.777696] [<ffffffff81086294>] ? __might_sleep+0x44/0x80 [ 487.777699] [<ffffffff815888c2>] ? __ww_mutex_lock+0x22/0x9c [ 487.777722] [<ffffffffa0104f64>] ? drm_modeset_lock+0x34/0xf0 [drm] [ 487.777733] [<ffffffffa0148d9e>] restore_fbdev_mode+0xee/0x2a0 [drm_kms_helper] [ 487.777742] [<ffffffffa014afce>] drm_fb_helper_restore_fbdev_mode_unlocked+0x2e/0x70 [drm_kms_helper] [ 487.777748] [<ffffffffa014b037>] drm_fb_helper_set_par+0x27/0x50 [drm_kms_helper] [ 487.777752] [<ffffffff8134560c>] fb_set_var+0x18c/0x3f0 [ 487.777777] [<ffffffffa02a9b0a>] ? __ext4_handle_dirty_metadata+0x8a/0x210 [ext4] [ 487.777783] [<ffffffff8133cb97>] fbcon_blank+0x1b7/0x2b0 [ 487.777790] [<ffffffff813be2a3>] do_unblank_screen+0xb3/0x1c0 [ 487.777795] [<ffffffff813b5aba>] vt_ioctl+0x118a/0x1210 [ 487.777801] [<ffffffff813a8fe0>] tty_ioctl+0x3f0/0xc90 [ 487.777808] [<ffffffff81172018>] ? kzfree+0x28/0x30 [ 487.777813] [<ffffffff811e053f>] ? mntput+0x1f/0x30 [ 487.777817] [<ffffffff811d3f5d>] do_vfs_ioctl+0x30d/0x570 [ 487.777822] [<ffffffff8107ed3a>] ? task_work_run+0x8a/0xa0 [ 487.777825] [<ffffffff811d4234>] SyS_ioctl+0x74/0x80 [ 487.777829] [<ffffffff8158aeae>] entry_SYSCALL_64_fastpath+0x12/0x71 [ 487.777851] Code: 65 ff 0d ce 02 a8 7e 5d c3 ba 01 00 00 00 f0 0f b1 17 85 c0 75 e8 b0 01 5d c3 0f 1f 00 65 ff 05 b1 02 a8 7e 31 c0 ba 01 00 00 00 <f0> 0f b1 17 85 c0 75 01 c3 55 89 c6 48 89 e5 e8 4e f5 b1 ff 5d [ 487.777854] RIP [<ffffffff8158aaee>] _raw_spin_lock+0xe/0x30 [ 487.777855] RSP <ffff8808696d79c0> [ 487.777856] CR2: 0000000000000060 [ 487.777860] ---[ end trace 672a2cd555e0ebd3 ]--- The cursor code may be entered with file_priv == NULL && handle == NULL. The problem was introduced by: "bf89209 drm/mga200g: Hold a proper reference for cursor_set" which calls drm_gem_object_lookup(dev, file_priv...). Previously this wasn't a problem because we checked the handle. Move the check early in the function can fix the problem. Signed-off-by: Rui Wang <rui.y.wang@intel.com> Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch> Signed-off-by: Dave Airlie <airlied@redhat.com>
1 parent e6c84ac
mount.h
#include <linux/mount.h>
#include <linux/seq_file.h>
#include <linux/poll.h>
#include <linux/ns_common.h>
#include <linux/fs_pin.h>
struct mnt_namespace {
atomic_t count;
struct ns_common ns;
struct mount * root;
struct list_head list;
struct user_namespace *user_ns;
u64 seq; /* Sequence number to prevent loops */
wait_queue_head_t poll;
u64 event;
};
struct mnt_pcp {
int mnt_count;
int mnt_writers;
};
struct mountpoint {
struct hlist_node m_hash;
struct dentry *m_dentry;
struct hlist_head m_list;
int m_count;
};
struct mount {
struct hlist_node mnt_hash;
struct mount *mnt_parent;
struct dentry *mnt_mountpoint;
struct vfsmount mnt;
union {
struct rcu_head mnt_rcu;
struct llist_node mnt_llist;
};
#ifdef CONFIG_SMP
struct mnt_pcp __percpu *mnt_pcp;
#else
int mnt_count;
int mnt_writers;
#endif
struct list_head mnt_mounts; /* list of children, anchored here */
struct list_head mnt_child; /* and going through their mnt_child */
struct list_head mnt_instance; /* mount instance on sb->s_mounts */
const char *mnt_devname; /* Name of device e.g. /dev/dsk/hda1 */
struct list_head mnt_list;
struct list_head mnt_expire; /* link in fs-specific expiry list */
struct list_head mnt_share; /* circular list of shared mounts */
struct list_head mnt_slave_list;/* list of slave mounts */
struct list_head mnt_slave; /* slave list entry */
struct mount *mnt_master; /* slave is on master->mnt_slave_list */
struct mnt_namespace *mnt_ns; /* containing namespace */
struct mountpoint *mnt_mp; /* where is it mounted */
struct hlist_node mnt_mp_list; /* list mounts with the same mountpoint */
#ifdef CONFIG_FSNOTIFY
struct hlist_head mnt_fsnotify_marks;
__u32 mnt_fsnotify_mask;
#endif
int mnt_id; /* mount identifier */
int mnt_group_id; /* peer group identifier */
int mnt_expiry_mark; /* true if marked for expiry */
struct hlist_head mnt_pins;
struct fs_pin mnt_umount;
struct dentry *mnt_ex_mountpoint;
};
#define MNT_NS_INTERNAL ERR_PTR(-EINVAL) /* distinct from any mnt_namespace */
static inline struct mount *real_mount(struct vfsmount *mnt)
{
return container_of(mnt, struct mount, mnt);
}
static inline int mnt_has_parent(struct mount *mnt)
{
return mnt != mnt->mnt_parent;
}
static inline int is_mounted(struct vfsmount *mnt)
{
/* neither detached nor internal? */
return !IS_ERR_OR_NULL(real_mount(mnt)->mnt_ns);
}
extern struct mount *__lookup_mnt(struct vfsmount *, struct dentry *);
extern struct mount *__lookup_mnt_last(struct vfsmount *, struct dentry *);
extern int __legitimize_mnt(struct vfsmount *, unsigned);
extern bool legitimize_mnt(struct vfsmount *, unsigned);
extern void __detach_mounts(struct dentry *dentry);
static inline void detach_mounts(struct dentry *dentry)
{
if (!d_mountpoint(dentry))
return;
__detach_mounts(dentry);
}
static inline void get_mnt_ns(struct mnt_namespace *ns)
{
atomic_inc(&ns->count);
}
extern seqlock_t mount_lock;
static inline void lock_mount_hash(void)
{
write_seqlock(&mount_lock);
}
static inline void unlock_mount_hash(void)
{
write_sequnlock(&mount_lock);
}
struct proc_mounts {
struct mnt_namespace *ns;
struct path root;
int (*show)(struct seq_file *, struct vfsmount *);
void *cached_mount;
u64 cached_event;
loff_t cached_index;
};
extern const struct seq_operations mounts_op;
extern bool __is_local_mountpoint(struct dentry *dentry);
static inline bool is_local_mountpoint(struct dentry *dentry)
{
if (!d_mountpoint(dentry))
return false;
return __is_local_mountpoint(dentry);
}
Computing file changes ...
