From: manfreds <manfreds@colorfullife.com>
To: viro@math.psu.edu
Cc: linux-kernel@vger.rutgers.edu, linux-mm@kvack.org
Subject: vma_list_sem
Date: Tue, 12 Oct 1999 19:50:07 +0200 (CEST) [thread overview]
Message-ID: <Pine.LNX.4.10.9910121943300.17128-100000@clmsdevli> (raw)
I've merged your patch and my patch, the result is below.
It still contains the complete debugging code, and I've not
yet performed any low-memory testing.
I found one more find_vma() caller which performs no locking:
fs/super.c: copy_mount_options().
Unfortunately, I found no clean solution for this function, but
I think my fix is acceptable. [there is an obscure race possible,
a multi-threaded application could fail with -EFAULT although
all parameters are valid].
--
Manfred
<<<<<<<<<<<<<<<<<<<<<<<<<<<
// $Header$
// Kernel Version:
// VERSION = 2
// PATCHLEVEL = 3
// SUBLEVEL = 20
// EXTRAVERSION =
diff -r -u 2.3/arch/i386/mm/fault.c build-2.3/arch/i386/mm/fault.c
--- 2.3/arch/i386/mm/fault.c Tue Aug 10 09:53:55 1999
+++ build-2.3/arch/i386/mm/fault.c Tue Oct 12 19:39:39 1999
@@ -35,6 +35,7 @@
if (!size)
return 1;
+ down(¤t->mm->mmap_sem);
vma = find_vma(current->mm, start);
if (!vma)
goto bad_area;
@@ -64,6 +65,7 @@
if (!(vma->vm_flags & VM_WRITE))
goto bad_area;;
}
+ up(¤t->mm->mmap_sem);
return 1;
check_stack:
@@ -73,6 +75,7 @@
goto good_area;
bad_area:
+ up(¤t->mm->mmap_sem);
return 0;
}
diff -r -u 2.3/arch/m68k/kernel/sys_m68k.c build-2.3/arch/m68k/kernel/sys_m68k.c
--- 2.3/arch/m68k/kernel/sys_m68k.c Tue Jan 19 19:58:34 1999
+++ build-2.3/arch/m68k/kernel/sys_m68k.c Tue Oct 12 18:31:36 1999
@@ -535,6 +535,7 @@
int ret = -EINVAL;
lock_kernel();
+ down(¤t->mm->mmap_sem);
if (scope < FLUSH_SCOPE_LINE || scope > FLUSH_SCOPE_ALL ||
cache & ~FLUSH_CACHE_BOTH)
goto out;
@@ -591,6 +592,7 @@
ret = cache_flush_060 (addr, scope, cache, len);
}
out:
+ up(¤t->mm->mmap_sem);
unlock_kernel();
return ret;
}
diff -r -u 2.3/arch/mips/kernel/sysirix.c build-2.3/arch/mips/kernel/sysirix.c
--- 2.3/arch/mips/kernel/sysirix.c Thu Jul 1 15:05:14 1999
+++ build-2.3/arch/mips/kernel/sysirix.c Tue Oct 12 18:31:36 1999
@@ -534,6 +534,7 @@
int ret;
lock_kernel();
+ down(¤t->mm->mmap_sem);
if (brk < current->mm->end_code) {
ret = -ENOMEM;
goto out;
@@ -591,6 +592,7 @@
ret = 0;
out:
+ up(¤t->mm->mmap_sem);
unlock_kernel();
return ret;
}
diff -r -u 2.3/arch/sh/mm/fault.c build-2.3/arch/sh/mm/fault.c
--- 2.3/arch/sh/mm/fault.c Tue Sep 7 23:35:59 1999
+++ build-2.3/arch/sh/mm/fault.c Tue Oct 12 18:31:36 1999
@@ -38,6 +38,7 @@
if (!size)
return 1;
+ down(¤t->mm->mmap_sem);
vma = find_vma(current->mm, start);
if (!vma)
goto bad_area;
@@ -67,6 +68,7 @@
if (!(vma->vm_flags & VM_WRITE))
goto bad_area;;
}
+ up(¤t->mm->mmap_sem);
return 1;
check_stack:
@@ -76,6 +78,7 @@
goto good_area;
bad_area:
+ up(¤t->mm->mmap_sem);
return 0;
}
diff -r -u 2.3/fs/binfmt_aout.c build-2.3/fs/binfmt_aout.c
--- 2.3/fs/binfmt_aout.c Wed Sep 1 18:22:44 1999
+++ build-2.3/fs/binfmt_aout.c Tue Oct 12 19:33:17 1999
@@ -45,7 +45,9 @@
end = PAGE_ALIGN(end);
if (end <= start)
return;
+ down(¤t->mm->mmap_sem);
do_brk(start, end - start);
+ up(¤t->mm->mmap_sem);
}
/*
@@ -383,12 +385,14 @@
goto beyond_if;
}
+ down(¤t->mm->mmap_sem);
error = do_mmap(file, N_TXTADDR(ex), ex.a_text,
PROT_READ | PROT_EXEC,
MAP_FIXED | MAP_PRIVATE | MAP_DENYWRITE | MAP_EXECUTABLE,
fd_offset);
if (error != N_TXTADDR(ex)) {
+ up(¤t->mm->mmap_sem);
fput(file);
sys_close(fd);
send_sig(SIGKILL, current, 0);
@@ -399,6 +403,7 @@
PROT_READ | PROT_WRITE | PROT_EXEC,
MAP_FIXED | MAP_PRIVATE | MAP_DENYWRITE | MAP_EXECUTABLE,
fd_offset + ex.a_text);
+ up(¤t->mm->mmap_sem);
fput(file);
sys_close(fd);
if (error != N_DATADDR(ex)) {
@@ -504,9 +509,11 @@
file->f_dentry->d_name.name
);
+ down(¤t->mm->mmap_sem);
do_mmap(NULL, start_addr & PAGE_MASK, ex.a_text + ex.a_data + ex.a_bss,
PROT_READ | PROT_WRITE | PROT_EXEC,
MAP_FIXED| MAP_PRIVATE, 0);
+ up(¤t->mm->mmap_sem);
read_exec(file->f_dentry, N_TXTOFF(ex),
(char *)start_addr, ex.a_text + ex.a_data, 0);
@@ -517,10 +524,12 @@
goto out_putf;
}
/* Now use mmap to map the library into memory. */
+ down(¤t->mm->mmap_sem);
error = do_mmap(file, start_addr, ex.a_text + ex.a_data,
PROT_READ | PROT_WRITE | PROT_EXEC,
MAP_FIXED | MAP_PRIVATE | MAP_DENYWRITE,
N_TXTOFF(ex));
+ up(¤t->mm->mmap_sem);
retval = error;
if (error != start_addr)
goto out_putf;
diff -r -u 2.3/fs/binfmt_elf.c build-2.3/fs/binfmt_elf.c
--- 2.3/fs/binfmt_elf.c Tue Aug 10 09:54:23 1999
+++ build-2.3/fs/binfmt_elf.c Tue Oct 12 19:33:04 1999
@@ -73,7 +73,9 @@
end = ELF_PAGEALIGN(end);
if (end <= start)
return;
+ down(¤t->mm->mmap_sem);
do_brk(start, end - start);
+ up(¤t->mm->mmap_sem);
}
@@ -277,12 +279,14 @@
#endif
}
+ down(¤t->mm->mmap_sem);
map_addr = do_mmap(file,
load_addr + ELF_PAGESTART(vaddr),
eppnt->p_filesz + ELF_PAGEOFFSET(eppnt->p_vaddr),
elf_prot,
elf_type,
eppnt->p_offset - ELF_PAGEOFFSET(eppnt->p_vaddr));
+ up(¤t->mm->mmap_sem);
if (map_addr > -1024UL) /* Real error */
goto out_close;
@@ -626,12 +630,13 @@
elf_flags |= MAP_FIXED;
}
+ down(¤t->mm->mmap_sem);
error = do_mmap(file, ELF_PAGESTART(load_bias + vaddr),
(elf_ppnt->p_filesz +
ELF_PAGEOFFSET(elf_ppnt->p_vaddr)),
elf_prot, elf_flags, (elf_ppnt->p_offset -
ELF_PAGEOFFSET(elf_ppnt->p_vaddr)));
-
+ up(¤t->mm->mmap_sem);
if (!load_addr_set) {
load_addr_set = 1;
load_addr = (elf_ppnt->p_vaddr - elf_ppnt->p_offset);
@@ -745,8 +750,10 @@
Since we do not have the power to recompile these, we
emulate the SVr4 behavior. Sigh. */
/* N.B. Shouldn't the size here be PAGE_SIZE?? */
+ down(¤t->mm->mmap_sem);
error = do_mmap(NULL, 0, 4096, PROT_READ | PROT_EXEC,
MAP_FIXED | MAP_PRIVATE, 0);
+ up(¤t->mm->mmap_sem);
}
#ifdef ELF_PLAT_INIT
@@ -857,6 +864,7 @@
while (elf_phdata->p_type != PT_LOAD) elf_phdata++;
/* Now use mmap to map the library into memory. */
+ down(¤t->mm->mmap_sem);
error = do_mmap(file,
ELF_PAGESTART(elf_phdata->p_vaddr),
(elf_phdata->p_filesz +
@@ -865,6 +873,7 @@
MAP_FIXED | MAP_PRIVATE | MAP_DENYWRITE,
(elf_phdata->p_offset -
ELF_PAGEOFFSET(elf_phdata->p_vaddr)));
+ up(¤t->mm->mmap_sem);
if (error != ELF_PAGESTART(elf_phdata->p_vaddr))
goto out_free_ph;
diff -r -u 2.3/fs/exec.c build-2.3/fs/exec.c
--- 2.3/fs/exec.c Tue Oct 12 18:02:40 1999
+++ build-2.3/fs/exec.c Tue Oct 12 19:10:17 1999
@@ -265,6 +265,7 @@
if (!mpnt)
return -ENOMEM;
+ down(¤t->mm->mmap_sem);
{
mpnt->vm_mm = current->mm;
mpnt->vm_start = PAGE_MASK & (unsigned long) bprm->p;
@@ -278,6 +279,7 @@
insert_vm_struct(current->mm, mpnt);
current->mm->total_vm = (mpnt->vm_end - mpnt->vm_start) >> PAGE_SHIFT;
}
+ up(¤t->mm->mmap_sem);
for (i = 0 ; i < MAX_ARG_PAGES ; i++) {
if (bprm->page[i]) {
diff -r -u 2.3/fs/super.c build-2.3/fs/super.c
--- 2.3/fs/super.c Wed Sep 1 18:22:45 1999
+++ build-2.3/fs/super.c Tue Oct 12 19:37:26 1999
@@ -977,7 +977,7 @@
static int copy_mount_options (const void * data, unsigned long *where)
{
- int i;
+ unsigned long i;
unsigned long page;
struct vm_area_struct * vma;
@@ -985,6 +985,10 @@
if (!data)
return 0;
+ if (!(page = __get_free_page(GFP_KERNEL))) {
+ return -ENOMEM;
+ }
+ down(¤t->mm->mmap_sem);
vma = find_vma(current->mm, (unsigned long) data);
if (!vma || (unsigned long) data < vma->vm_start)
return -EFAULT;
@@ -993,9 +997,8 @@
i = vma->vm_end - (unsigned long) data;
if (PAGE_SIZE <= (unsigned long) i)
i = PAGE_SIZE-1;
- if (!(page = __get_free_page(GFP_KERNEL))) {
- return -ENOMEM;
- }
+ up(¤t->mm->mmap_sem);
+
if (copy_from_user((void *) page,data,i)) {
free_page(page);
return -EFAULT;
diff -r -u 2.3/include/linux/sched.h build-2.3/include/linux/sched.h
--- 2.3/include/linux/sched.h Tue Oct 12 18:02:40 1999
+++ build-2.3/include/linux/sched.h Tue Oct 12 18:04:10 1999
@@ -213,6 +213,7 @@
atomic_t mm_count; /* How many references to "struct mm_struct" (users count as 1) */
int map_count; /* number of VMAs */
struct semaphore mmap_sem;
+ struct semaphore vma_list_sem;
spinlock_t page_table_lock;
unsigned long context;
unsigned long start_code, end_code, start_data, end_data;
@@ -235,6 +236,7 @@
swapper_pg_dir, \
ATOMIC_INIT(2), ATOMIC_INIT(1), 1, \
__MUTEX_INITIALIZER(name.mmap_sem), \
+ __MUTEX_INITIALIZER(name.vma_list_sem), \
SPIN_LOCK_UNLOCKED, \
0, \
0, 0, 0, 0, \
diff -r -u 2.3/kernel/fork.c build-2.3/kernel/fork.c
--- 2.3/kernel/fork.c Tue Oct 12 18:02:40 1999
+++ build-2.3/kernel/fork.c Tue Oct 12 18:02:24 1999
@@ -303,6 +303,7 @@
atomic_set(&mm->mm_users, 1);
atomic_set(&mm->mm_count, 1);
init_MUTEX(&mm->mmap_sem);
+ init_MUTEX(&mm->vma_list_sem);
mm->page_table_lock = SPIN_LOCK_UNLOCKED;
mm->pgd = pgd_alloc();
if (mm->pgd)
diff -r -u 2.3/kernel/ptrace.c build-2.3/kernel/ptrace.c
--- 2.3/kernel/ptrace.c Wed Sep 1 18:22:53 1999
+++ build-2.3/kernel/ptrace.c Tue Oct 12 19:32:52 1999
@@ -79,14 +79,15 @@
int access_process_vm(struct task_struct *tsk, unsigned long addr, void *buf, int len, int write)
{
- int copied;
- struct vm_area_struct * vma = find_extend_vma(tsk, addr);
+ int copied = 0;
+ struct vm_area_struct * vma;
+
+ down(&tsk->mm->mmap_sem);
+ vma = find_extend_vma(tsk, addr);
if (!vma)
- return 0;
+ goto out;
- down(&tsk->mm->mmap_sem);
- copied = 0;
for (;;) {
unsigned long offset = addr & ~PAGE_MASK;
int this_len = PAGE_SIZE - offset;
@@ -115,6 +116,7 @@
vma = vma->vm_next;
}
+out:
up(&tsk->mm->mmap_sem);
return copied;
}
diff -r -u 2.3/mm/mmap.c build-2.3/mm/mmap.c
--- 2.3/mm/mmap.c Tue Sep 7 23:36:11 1999
+++ build-2.3/mm/mmap.c Tue Oct 12 19:34:12 1999
@@ -16,6 +16,129 @@
#include <asm/uaccess.h>
#include <asm/pgtable.h>
+#define MMAP_DEBUG 1
+
+#if defined(__SMP__) && defined(MMAP_DEBUG)
+
+#ifdef __i386__
+extern int kstack_depth_to_print;
+#define VMALLOC_OFFSET (8*1024*1024)
+#define MODULE_RANGE (8*1024*1024)
+
+extern unsigned long _stext;
+extern unsigned long _etext;
+
+void show_stack(void)
+{
+ unsigned long *stack, addr, module_start, module_end;
+ int i;
+ unsigned long esp;
+ __asm__("mov %%esp,%0; ":"=r" (esp));
+
+ printk("\nStack: ");
+ stack = (unsigned long *) esp;
+ for(i=0; i < 2*kstack_depth_to_print; i++) {
+ if (((long) stack & 4095) == 0)
+ break;
+ if (i && ((i % 8) == 0))
+ printk("\n ");
+ printk("%08lx ", *stack++);
+ }
+ printk("\nCall Trace: ");
+ stack = (unsigned long *) esp;
+ i = 1;
+ module_start = PAGE_OFFSET + (max_mapnr << PAGE_SHIFT);
+ module_start = ((module_start + VMALLOC_OFFSET) & ~(VMALLOC_OFFSET-1));
+ module_end = module_start + MODULE_RANGE;
+ while (((long) stack & 4095) != 0) {
+ addr = *stack++;
+ /*
+ * If the address is either in the text segment of the
+ * kernel, or in the region which contains vmalloc'ed
+ * memory, it *may* be the address of a calling
+ * routine; if so, print it so that someone tracing
+ * down the cause of the crash will be able to figure
+ * out the call path that was taken.
+ */
+ if (((addr >= (unsigned long) &_stext) &&
+ (addr <= (unsigned long) &_etext)) ||
+ ((addr >= module_start) && (addr <= module_end))) {
+ if (i && ((i % 8) == 0))
+ printk("\n ");
+ printk("[<%08lx>] ", addr);
+ i++;
+ }
+ }
+}
+#else
+#define show_stack() (void)0
+#endif
+
+
+static inline int test_down(struct semaphore* sem)
+{
+ if(!down_trylock(sem)) {
+ up(sem);
+ return 0;
+ }
+ return 1;
+}
+static inline void assert_down(struct semaphore* sem)
+{
+ if(!test_down(sem)) {
+ printk("semaphore not acquired by %lxh.\n",__builtin_return_address(0));
+ show_stack();
+ }
+}
+
+void assert_up(struct semaphore* sem)
+{
+ if(test_down(sem)) {
+ printk("semaphore acquired by %lxh.\n",__builtin_return_address(0));
+ show_stack();
+ }
+}
+
+static inline void test_vmareadlock(struct mm_struct * mm)
+{
+ if(test_down(&mm->mmap_sem))
+ return;
+ if(test_down(&mm->vma_list_sem))
+ return;
+ printk("test_vamreadlock() failed %lxh.\n",__builtin_return_address(0));
+ show_stack();
+}
+
+static inline void test_vmawritelock(struct mm_struct *mm)
+{
+ if(test_down(&mm->mmap_sem) && test_down(&mm->vma_list_sem))
+ return;
+ printk("test_vmawritelock(): failed %lxh.\n",__builtin_return_address(0));
+ show_stack();
+}
+
+#else
+
+static inline void assert_down(struct semaphore* sem)
+{
+ sem;
+}
+void assert_up(struct semaphore* sem)
+{
+ sem;
+}
+static inline void test_vmareadlock(struct mm_struct * mm)
+{
+ mm;
+}
+
+static inline void test_vmawritelock(struct mm_struct *mm)
+{
+ mm;
+}
+
+#endif
+
/* description of effects of mapping type and prot in current implementation.
* this is due to the limited x86 page protection hardware. The expected
* behavior is in parens:
@@ -183,7 +306,8 @@
/* offset overflow? */
if (off + len < off)
return -EINVAL;
-
+
+ assert_down(&mm->mmap_sem);
/* Too many mappings? */
if (mm->map_count > MAX_MAP_COUNT)
return -ENOMEM;
@@ -358,6 +482,7 @@
addr = TASK_UNMAPPED_BASE;
addr = PAGE_ALIGN(addr);
+ test_vmareadlock(current->mm);
for (vmm = find_vma(current->mm, addr); ; vmm = vmm->vm_next) {
/* At this point: (!vmm || addr < vmm->vm_end). */
if (TASK_SIZE - len < addr)
@@ -378,6 +503,7 @@
struct vm_area_struct *vma = NULL;
if (mm) {
+ test_vmareadlock(mm);
/* Check the cache first. */
/* (Cache hit rate is typically around 35%.) */
vma = mm->mmap_cache;
@@ -415,6 +541,7 @@
struct vm_area_struct **pprev)
{
if (mm) {
+ test_vmareadlock(mm);
if (!mm->mmap_avl) {
/* Go through the linear list. */
struct vm_area_struct * prev = NULL;
@@ -579,6 +706,7 @@
unsigned long first = start & PGDIR_MASK;
unsigned long last = (end + PGDIR_SIZE - 1) & PGDIR_MASK;
+ test_vmareadlock(mm);
if (!prev) {
prev = mm->mmap;
if (!prev)
@@ -633,6 +761,7 @@
* on the list. If nothing is put on, nothing is affected.
*/
mm = current->mm;
+ assert_down(&mm->mmap_sem);
mpnt = find_vma_prev(mm, addr, &prev);
if (!mpnt)
return 0;
@@ -654,6 +783,7 @@
if (!extra)
return -ENOMEM;
+ down(&mm->vma_list_sem);
npp = (prev ? &prev->vm_next : &mm->mmap);
free = NULL;
for ( ; mpnt && mpnt->vm_start < addr+len; mpnt = *npp) {
@@ -669,6 +799,7 @@
* If the one of the segments is only being partially unmapped,
* it will put new vm_area_struct(s) into the address space.
*/
+ up(&mm->vma_list_sem);
while ((mpnt = free) != NULL) {
unsigned long st, end, size;
@@ -678,11 +809,10 @@
end = addr+len;
end = end > mpnt->vm_end ? mpnt->vm_end : end;
size = end - st;
+
- lock_kernel();
if (mpnt->vm_ops && mpnt->vm_ops->unmap)
mpnt->vm_ops->unmap(mpnt, st, size);
- unlock_kernel();
remove_shared_vm_struct(mpnt);
mm->map_count--;
@@ -732,6 +862,7 @@
if (!len)
return addr;
+ assert_down(&mm->mmap_sem);
/*
* mlock MCL_FUTURE?
*/
@@ -855,6 +986,8 @@
struct vm_area_struct **pprev;
struct file * file;
+ assert_down(&mm->mmap_sem);
+ down(&mm->vma_list_sem);
if (!mm->mmap_avl) {
pprev = &mm->mmap;
while (*pprev && (*pprev)->vm_start <= vmp->vm_start)
@@ -887,6 +1020,7 @@
vmp->vm_pprev_share = &inode->i_mmap;
spin_unlock(&inode->i_shared_lock);
}
+ up(&mm->vma_list_sem);
}
/* Merge the list of memory segments if possible.
@@ -905,6 +1039,8 @@
if (!mpnt)
return;
+ assert_down(&mm->mmap_sem);
+ down(&mm->vma_list_sem);
if (prev1) {
prev = prev1;
} else {
@@ -957,6 +1093,7 @@
mpnt = prev;
}
mm->mmap_cache = NULL; /* Kill the cache. */
+ up(&mm->vma_list_sem);
}
void __init vma_init(void)
diff -r -u 2.3/mm/vmscan.c build-2.3/mm/vmscan.c
--- 2.3/mm/vmscan.c Sat Oct 9 22:51:29 1999
+++ build-2.3/mm/vmscan.c Tue Oct 12 18:38:30 1999
@@ -295,6 +295,8 @@
/*
* Find the proper vm-area
*/
+ assert_up(&mm->vma_list_sem);
+ down(&mm->vma_list_sem);
vma = find_vma(mm, address);
if (vma) {
if (address < vma->vm_start)
@@ -302,14 +304,17 @@
for (;;) {
int result = swap_out_vma(vma, address, gfp_mask);
- if (result)
+ if (result) {
+ up(&mm->vma_list_sem);
return result;
+ }
vma = vma->vm_next;
if (!vma)
break;
address = vma->vm_start;
}
}
+ up(&mm->vma_list_sem);
/* We didn't find anything for the process */
mm->swap_cnt = 0;
>>>>>>>>>>>>>>>>>>>>>>>>>>>
-
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next reply other threads:[~1999-10-12 17:58 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
1999-10-12 17:50 manfreds [this message]
1999-10-12 17:53 ` vma_list_sem Manfred Spraul
1999-10-12 18:48 ` vma_list_sem Alexander Viro
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