Revision 6946bd636364effce06ea46fe8f8cd6e2edb004e authored by Peter Zijlstra on 27 August 2006, 08:23:31 UTC, committed by Linus Torvalds on 27 August 2006, 18:01:29 UTC
On Wed, 2006-08-09 at 07:57 +0200, Rolf Eike Beer wrote: > ============================================= > [ INFO: possible recursive locking detected ] > --------------------------------------------- > parted/7929 is trying to acquire lock: > (&bdev->bd_mutex){--..}, at: [<c105eb8d>] __blkdev_put+0x1e/0x13c > > but task is already holding lock: > (&bdev->bd_mutex){--..}, at: [<c105eec6>] do_open+0x72/0x3a8 > > other info that might help us debug this: > 1 lock held by parted/7929: > #0: (&bdev->bd_mutex){--..}, at: [<c105eec6>] do_open+0x72/0x3a8 > stack backtrace: > [<c1003aad>] show_trace_log_lvl+0x58/0x15b > [<c100495f>] show_trace+0xd/0x10 > [<c1004979>] dump_stack+0x17/0x1a > [<c102dee5>] __lock_acquire+0x753/0x99c > [<c102e3b0>] lock_acquire+0x4a/0x6a > [<c1204501>] mutex_lock_nested+0xc8/0x20c > [<c105eb8d>] __blkdev_put+0x1e/0x13c > [<c105ecc4>] blkdev_put+0xa/0xc > [<c105f18a>] do_open+0x336/0x3a8 > [<c105f21b>] blkdev_open+0x1f/0x4c > [<c1057b40>] __dentry_open+0xc7/0x1aa > [<c1057c91>] nameidata_to_filp+0x1c/0x2e > [<c1057cd1>] do_filp_open+0x2e/0x35 > [<c1057dd7>] do_sys_open+0x38/0x68 > [<c1057e33>] sys_open+0x16/0x18 > [<c1002845>] sysenter_past_esp+0x56/0x8d OK, I'm having a look here; its all new to me so bear with me. blkdev_open() calls do_open(bdev, ...,BD_MUTEX_NORMAL) and takes mutex_lock_nested(&bdev->bd_mutex, BD_MUTEX_NORMAL) then something fails, and we're thrown to: out_first: where if (bdev != bdev->bd_contains) blkdev_put(bdev->bd_contains) which is __blkdev_put(bdev->bd_contains, BD_MUTEX_NORMAL) which does mutex_lock_nested(&bdev->bd_contains->bd_mutex, BD_MUTEX_NORMAL) <--- lockdep trigger When going to out_first, dbev->bd_contains is either bdev or whole, and since we take the branch it must be whole. So it seems to me the following patch would be the right one: [akpm@osdl.org: compile fix] Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Arjan van de Ven <arjan@linux.intel.com> Acked-by: NeilBrown <neilb@suse.de> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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desc.h
/* Written 2000 by Andi Kleen */
#ifndef __ARCH_DESC_H
#define __ARCH_DESC_H
#include <linux/threads.h>
#include <asm/ldt.h>
#ifndef __ASSEMBLY__
#include <linux/string.h>
#include <linux/smp.h>
#include <asm/segment.h>
#include <asm/mmu.h>
// 8 byte segment descriptor
struct desc_struct {
u16 limit0;
u16 base0;
unsigned base1 : 8, type : 4, s : 1, dpl : 2, p : 1;
unsigned limit : 4, avl : 1, l : 1, d : 1, g : 1, base2 : 8;
} __attribute__((packed));
struct n_desc_struct {
unsigned int a,b;
};
extern struct desc_struct cpu_gdt_table[GDT_ENTRIES];
enum {
GATE_INTERRUPT = 0xE,
GATE_TRAP = 0xF,
GATE_CALL = 0xC,
};
// 16byte gate
struct gate_struct {
u16 offset_low;
u16 segment;
unsigned ist : 3, zero0 : 5, type : 5, dpl : 2, p : 1;
u16 offset_middle;
u32 offset_high;
u32 zero1;
} __attribute__((packed));
#define PTR_LOW(x) ((unsigned long)(x) & 0xFFFF)
#define PTR_MIDDLE(x) (((unsigned long)(x) >> 16) & 0xFFFF)
#define PTR_HIGH(x) ((unsigned long)(x) >> 32)
enum {
DESC_TSS = 0x9,
DESC_LDT = 0x2,
};
// LDT or TSS descriptor in the GDT. 16 bytes.
struct ldttss_desc {
u16 limit0;
u16 base0;
unsigned base1 : 8, type : 5, dpl : 2, p : 1;
unsigned limit1 : 4, zero0 : 3, g : 1, base2 : 8;
u32 base3;
u32 zero1;
} __attribute__((packed));
struct desc_ptr {
unsigned short size;
unsigned long address;
} __attribute__((packed)) ;
#define load_TR_desc() asm volatile("ltr %w0"::"r" (GDT_ENTRY_TSS*8))
#define load_LDT_desc() asm volatile("lldt %w0"::"r" (GDT_ENTRY_LDT*8))
#define clear_LDT() asm volatile("lldt %w0"::"r" (0))
/*
* This is the ldt that every process will get unless we need
* something other than this.
*/
extern struct desc_struct default_ldt[];
extern struct gate_struct idt_table[];
extern struct desc_ptr cpu_gdt_descr[];
/* the cpu gdt accessor */
#define cpu_gdt(_cpu) ((struct desc_struct *)cpu_gdt_descr[_cpu].address)
static inline void _set_gate(void *adr, unsigned type, unsigned long func, unsigned dpl, unsigned ist)
{
struct gate_struct s;
s.offset_low = PTR_LOW(func);
s.segment = __KERNEL_CS;
s.ist = ist;
s.p = 1;
s.dpl = dpl;
s.zero0 = 0;
s.zero1 = 0;
s.type = type;
s.offset_middle = PTR_MIDDLE(func);
s.offset_high = PTR_HIGH(func);
/* does not need to be atomic because it is only done once at setup time */
memcpy(adr, &s, 16);
}
static inline void set_intr_gate(int nr, void *func)
{
BUG_ON((unsigned)nr > 0xFF);
_set_gate(&idt_table[nr], GATE_INTERRUPT, (unsigned long) func, 0, 0);
}
static inline void set_intr_gate_ist(int nr, void *func, unsigned ist)
{
BUG_ON((unsigned)nr > 0xFF);
_set_gate(&idt_table[nr], GATE_INTERRUPT, (unsigned long) func, 0, ist);
}
static inline void set_system_gate(int nr, void *func)
{
BUG_ON((unsigned)nr > 0xFF);
_set_gate(&idt_table[nr], GATE_INTERRUPT, (unsigned long) func, 3, 0);
}
static inline void set_system_gate_ist(int nr, void *func, unsigned ist)
{
_set_gate(&idt_table[nr], GATE_INTERRUPT, (unsigned long) func, 3, ist);
}
static inline void set_tssldt_descriptor(void *ptr, unsigned long tss, unsigned type,
unsigned size)
{
struct ldttss_desc d;
memset(&d,0,sizeof(d));
d.limit0 = size & 0xFFFF;
d.base0 = PTR_LOW(tss);
d.base1 = PTR_MIDDLE(tss) & 0xFF;
d.type = type;
d.p = 1;
d.limit1 = (size >> 16) & 0xF;
d.base2 = (PTR_MIDDLE(tss) >> 8) & 0xFF;
d.base3 = PTR_HIGH(tss);
memcpy(ptr, &d, 16);
}
static inline void set_tss_desc(unsigned cpu, void *addr)
{
/*
* sizeof(unsigned long) coming from an extra "long" at the end
* of the iobitmap. See tss_struct definition in processor.h
*
* -1? seg base+limit should be pointing to the address of the
* last valid byte
*/
set_tssldt_descriptor(&cpu_gdt(cpu)[GDT_ENTRY_TSS],
(unsigned long)addr, DESC_TSS,
IO_BITMAP_OFFSET + IO_BITMAP_BYTES + sizeof(unsigned long) - 1);
}
static inline void set_ldt_desc(unsigned cpu, void *addr, int size)
{
set_tssldt_descriptor(&cpu_gdt(cpu)[GDT_ENTRY_LDT], (unsigned long)addr,
DESC_LDT, size * 8 - 1);
}
static inline void set_seg_base(unsigned cpu, int entry, void *base)
{
struct desc_struct *d = &cpu_gdt(cpu)[entry];
u32 addr = (u32)(u64)base;
BUG_ON((u64)base >> 32);
d->base0 = addr & 0xffff;
d->base1 = (addr >> 16) & 0xff;
d->base2 = (addr >> 24) & 0xff;
}
#define LDT_entry_a(info) \
((((info)->base_addr & 0x0000ffff) << 16) | ((info)->limit & 0x0ffff))
/* Don't allow setting of the lm bit. It is useless anyways because
64bit system calls require __USER_CS. */
#define LDT_entry_b(info) \
(((info)->base_addr & 0xff000000) | \
(((info)->base_addr & 0x00ff0000) >> 16) | \
((info)->limit & 0xf0000) | \
(((info)->read_exec_only ^ 1) << 9) | \
((info)->contents << 10) | \
(((info)->seg_not_present ^ 1) << 15) | \
((info)->seg_32bit << 22) | \
((info)->limit_in_pages << 23) | \
((info)->useable << 20) | \
/* ((info)->lm << 21) | */ \
0x7000)
#define LDT_empty(info) (\
(info)->base_addr == 0 && \
(info)->limit == 0 && \
(info)->contents == 0 && \
(info)->read_exec_only == 1 && \
(info)->seg_32bit == 0 && \
(info)->limit_in_pages == 0 && \
(info)->seg_not_present == 1 && \
(info)->useable == 0 && \
(info)->lm == 0)
#if TLS_SIZE != 24
# error update this code.
#endif
static inline void load_TLS(struct thread_struct *t, unsigned int cpu)
{
u64 *gdt = (u64 *)(cpu_gdt(cpu) + GDT_ENTRY_TLS_MIN);
gdt[0] = t->tls_array[0];
gdt[1] = t->tls_array[1];
gdt[2] = t->tls_array[2];
}
/*
* load one particular LDT into the current CPU
*/
static inline void load_LDT_nolock (mm_context_t *pc, int cpu)
{
int count = pc->size;
if (likely(!count)) {
clear_LDT();
return;
}
set_ldt_desc(cpu, pc->ldt, count);
load_LDT_desc();
}
static inline void load_LDT(mm_context_t *pc)
{
int cpu = get_cpu();
load_LDT_nolock(pc, cpu);
put_cpu();
}
extern struct desc_ptr idt_descr;
#endif /* !__ASSEMBLY__ */
#endif
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