[PATCH] Fix mlockall for PROT_NONE mappings
From: Andi Kleen
Date: Thu Oct 09 2003 - 05:43:22 EST
The x86-64 ld.so always puts a PROT_NONE mapping into every 64bit process'
address space.
2a95791000-2a9586d000 ---p 00124000 03:01 788090 /lib64/libc.so.6
This broke mlockall on x86-64 which ran into this mapping and always
returned an error and stopped early before mlocking everything.
This patch fixes mlockall to ignore errors for such mappings.
I added a new argument force==2 to get_user_pages that means to ignore
SIGBUS or unaccessible pages errors. MAY_* is still checked for like
with the old force ==1, it just doesn't error out now for SIGBUS
errors on handle_mm_fault.
make_pages_present also has a new "tolerant" argument now that sets
force == 2. The patch sets it for mlockall and mmap (which didn't
check its return arguments), but not for mlock(). Arguably it could
be not set for mmap on a VM_LOCKED vma.
-Andi
diff -u linux-test7-work/mm/memory.c-o linux-test7-work/mm/memory.c
--- linux-test7-work/mm/memory.c-o 2003-10-09 00:29:01.000000000 +0200
+++ linux-test7-work/mm/memory.c 2003-12-04 11:27:43.000000000 +0100
@@ -674,12 +674,15 @@
static inline struct page *get_page_map(struct page *page)
{
+ if (!page)
+ return 0;
if (!pfn_valid(page_to_pfn(page)))
return 0;
return page;
}
+/* force == 2 means tolerate holes in the mapping */
int get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
unsigned long start, int len, int write, int force,
struct page **pages, struct vm_area_struct **vmas)
@@ -763,6 +766,10 @@
tsk->maj_flt++;
break;
case VM_FAULT_SIGBUS:
+ if (force == 2) {
+ map = NULL;
+ break;
+ }
return i ? i : -EFAULT;
case VM_FAULT_OOM:
return i ? i : -ENOMEM;
@@ -770,19 +777,22 @@
BUG();
}
spin_lock(&mm->page_table_lock);
+ if (!map)
+ break;
}
if (pages) {
pages[i] = get_page_map(map);
- if (!pages[i]) {
+ if (!pages[i] && force != 2) {
spin_unlock(&mm->page_table_lock);
while (i--)
page_cache_release(pages[i]);
i = -EFAULT;
goto out;
+ } else {
+ flush_dcache_page(pages[i]);
+ if (!PageReserved(pages[i]))
+ page_cache_get(pages[i]);
}
- flush_dcache_page(pages[i]);
- if (!PageReserved(pages[i]))
- page_cache_get(pages[i]);
}
if (vmas)
vmas[i] = vma;
@@ -1655,7 +1665,7 @@
return pmd_offset(pgd, address);
}
-int make_pages_present(unsigned long addr, unsigned long end)
+int make_pages_present(unsigned long addr, unsigned long end, int tolerant)
{
int ret, len, write;
struct vm_area_struct * vma;
@@ -1668,7 +1678,7 @@
BUG();
len = (end+PAGE_SIZE-1)/PAGE_SIZE-addr/PAGE_SIZE;
ret = get_user_pages(current, current->mm, addr,
- len, write, 0, NULL, NULL);
+ len, write, tolerant ? 2 : 0, NULL, NULL);
if (ret < 0)
return ret;
return ret == len ? 0 : -1;
diff -u linux-test7-work/mm/mlock.c-o linux-test7-work/mm/mlock.c
--- linux-test7-work/mm/mlock.c-o 2003-09-28 10:53:25.000000000 +0200
+++ linux-test7-work/mm/mlock.c 2003-12-04 10:58:22.000000000 +0100
@@ -10,7 +10,8 @@
static int mlock_fixup(struct vm_area_struct * vma,
- unsigned long start, unsigned long end, unsigned int newflags)
+ unsigned long start, unsigned long end, unsigned int newflags,
+ int tolerant)
{
struct mm_struct * mm = vma->vm_mm;
int pages;
@@ -43,7 +44,7 @@
pages = (end - start) >> PAGE_SHIFT;
if (newflags & VM_LOCKED) {
pages = -pages;
- ret = make_pages_present(start, end);
+ ret = make_pages_present(start, end, tolerant);
}
vma->vm_mm->locked_vm -= pages;
@@ -79,13 +80,13 @@
newflags &= ~VM_LOCKED;
if (vma->vm_end >= end) {
- error = mlock_fixup(vma, nstart, end, newflags);
+ error = mlock_fixup(vma, nstart, end, newflags, 0);
break;
}
tmp = vma->vm_end;
next = vma->vm_next;
- error = mlock_fixup(vma, nstart, tmp, newflags);
+ error = mlock_fixup(vma, nstart, tmp, newflags, 0);
if (error)
break;
nstart = tmp;
@@ -154,7 +155,7 @@
newflags = vma->vm_flags | VM_LOCKED;
if (!(flags & MCL_CURRENT))
newflags &= ~VM_LOCKED;
- error = mlock_fixup(vma, vma->vm_start, vma->vm_end, newflags);
+ error = mlock_fixup(vma, vma->vm_start, vma->vm_end, newflags, 1);
if (error)
break;
}
diff -u linux-test7-work/mm/mremap.c-o linux-test7-work/mm/mremap.c
--- linux-test7-work/mm/mremap.c-o 2003-09-11 04:12:42.000000000 +0200
+++ linux-test7-work/mm/mremap.c 2003-12-04 11:00:25.000000000 +0100
@@ -281,7 +281,7 @@
current->mm->locked_vm += new_len >> PAGE_SHIFT;
if (new_len > old_len)
make_pages_present(new_addr + old_len,
- new_addr + new_len);
+ new_addr + new_len, 2);
}
return new_addr;
}
@@ -405,7 +405,7 @@
if (vma->vm_flags & VM_LOCKED) {
current->mm->locked_vm += pages;
make_pages_present(addr + old_len,
- addr + new_len);
+ addr + new_len, 2);
}
ret = addr;
goto out;
diff -u linux-test7-work/mm/mmap.c-o linux-test7-work/mm/mmap.c
--- linux-test7-work/mm/mmap.c-o 2003-10-09 00:29:01.000000000 +0200
+++ linux-test7-work/mm/mmap.c 2003-12-04 11:02:17.000000000 +0100
@@ -655,7 +655,7 @@
mm->total_vm += len >> PAGE_SHIFT;
if (vm_flags & VM_LOCKED) {
mm->locked_vm += len >> PAGE_SHIFT;
- make_pages_present(addr, addr + len);
+ make_pages_present(addr, addr + len, 2);
}
if (flags & MAP_POPULATE) {
up_write(&mm->mmap_sem);
@@ -910,7 +910,7 @@
if (!prev || expand_stack(prev, addr))
return NULL;
if (prev->vm_flags & VM_LOCKED) {
- make_pages_present(addr, prev->vm_end);
+ make_pages_present(addr, prev->vm_end, 2);
}
return prev;
}
@@ -971,7 +971,7 @@
if (expand_stack(vma, addr))
return NULL;
if (vma->vm_flags & VM_LOCKED) {
- make_pages_present(addr, start);
+ make_pages_present(addr, start, 2);
}
return vma;
}
@@ -1345,7 +1345,7 @@
mm->total_vm += len >> PAGE_SHIFT;
if (flags & VM_LOCKED) {
mm->locked_vm += len >> PAGE_SHIFT;
- make_pages_present(addr, addr + len);
+ make_pages_present(addr, addr + len, 2);
}
return addr;
}
diff -u linux-test7-work/include/linux/mm.h-o linux-test7-work/include/linux/mm.h
--- linux-test7-work/include/linux/mm.h-o 2003-10-09 00:29:00.000000000 +0200
+++ linux-test7-work/include/linux/mm.h 2003-12-04 11:00:25.000000000 +0100
@@ -433,7 +433,7 @@
extern int install_page(struct mm_struct *mm, struct vm_area_struct *vma, unsigned long addr, struct page *page, pgprot_t prot);
extern int install_file_pte(struct mm_struct *mm, struct vm_area_struct *vma, unsigned long addr, unsigned long pgoff, pgprot_t prot);
extern int handle_mm_fault(struct mm_struct *mm,struct vm_area_struct *vma, unsigned long address, int write_access);
-extern int make_pages_present(unsigned long addr, unsigned long end);
+extern int make_pages_present(unsigned long addr, unsigned long end, int tolerant);
extern int access_process_vm(struct task_struct *tsk, unsigned long addr, void *buf, int len, int write);
extern long sys_remap_file_pages(unsigned long start, unsigned long size, unsigned long prot, unsigned long pgoff, unsigned long nonblock);
extern long sys_fadvise64_64(int fd, loff_t offset, loff_t len, int advice);
-
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