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Date: Thu, 08 May 2008 16:15:32 -0700
From: Dave Hansen <dave@...ux.vnet.ibm.com>
To: Hans Rosenfeld <hans.rosenfeld@....com>
Cc: Hugh Dickins <hugh@...itas.com>,
Nishanth Aravamudan <nacc@...ibm.com>,
Ingo Molnar <mingo@...e.hu>,
Jeff Chua <jeff.chua.linux@...il.com>,
Thomas Gleixner <tglx@...utronix.de>,
"H. Peter Anvin" <hpa@...or.com>,
Gabriel C <nix.or.die@...glemail.com>,
Arjan van de Ven <arjan@...ux.intel.com>,
Matt Mackall <mpm@...enic.com>, linux-kernel@...r.kernel.org,
linux-mm@...ck.org
Subject: Re: [PATCH] x86: fix PAE pmd_bad bootup warning
Here's one quick stab at a solution. I figured that we already pass
that 'private' variable around. This patch just sticks that variable
*in* the mm_walk and also makes the caller fill in an 'mm' as well.
Then, we just pass the actual mm_walk around.
Maybe we should just stick the VMA in the mm_walk as well, and have the
common code keep it up to date with the addresses currently being
walked.
Sadly, I didn't quite get enough time to flesh this idea out very far
today, and I'll be offline for a couple of days now. But, if someone
wants to go this route, I thought this might be useful.
---
linux-2.6.git-dave/fs/proc/task_mmu.c | 45 +++++++++++++++++++---------------
linux-2.6.git-dave/include/linux/mm.h | 17 ++++++------
linux-2.6.git-dave/mm/pagewalk.c | 41 +++++++++++++++---------------
3 files changed, 56 insertions(+), 47 deletions(-)
diff -puN mm/pagewalk.c~pass-mm-into-pagewalkers mm/pagewalk.c
--- linux-2.6.git/mm/pagewalk.c~pass-mm-into-pagewalkers 2008-05-08 15:49:47.000000000 -0700
+++ linux-2.6.git-dave/mm/pagewalk.c 2008-05-08 15:49:54.000000000 -0700
@@ -3,14 +3,14 @@
#include <linux/sched.h>
static int walk_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end,
- const struct mm_walk *walk, void *private)
+ struct mm_walk *walk)
{
pte_t *pte;
int err = 0;
pte = pte_offset_map(pmd, addr);
for (;;) {
- err = walk->pte_entry(pte, addr, addr + PAGE_SIZE, private);
+ err = walk->pte_entry(pte, addr, addr + PAGE_SIZE, walk);
if (err)
break;
addr += PAGE_SIZE;
@@ -24,7 +24,7 @@ static int walk_pte_range(pmd_t *pmd, un
}
static int walk_pmd_range(pud_t *pud, unsigned long addr, unsigned long end,
- const struct mm_walk *walk, void *private)
+ struct mm_walk *walk)
{
pmd_t *pmd;
unsigned long next;
@@ -35,15 +35,15 @@ static int walk_pmd_range(pud_t *pud, un
next = pmd_addr_end(addr, end);
if (pmd_none_or_clear_bad(pmd)) {
if (walk->pte_hole)
- err = walk->pte_hole(addr, next, private);
+ err = walk->pte_hole(addr, next, walk);
if (err)
break;
continue;
}
if (walk->pmd_entry)
- err = walk->pmd_entry(pmd, addr, next, private);
+ err = walk->pmd_entry(pmd, addr, next, walk);
if (!err && walk->pte_entry)
- err = walk_pte_range(pmd, addr, next, walk, private);
+ err = walk_pte_range(pmd, addr, next, walk);
if (err)
break;
} while (pmd++, addr = next, addr != end);
@@ -52,7 +52,7 @@ static int walk_pmd_range(pud_t *pud, un
}
static int walk_pud_range(pgd_t *pgd, unsigned long addr, unsigned long end,
- const struct mm_walk *walk, void *private)
+ struct mm_walk *walk)
{
pud_t *pud;
unsigned long next;
@@ -63,15 +63,15 @@ static int walk_pud_range(pgd_t *pgd, un
next = pud_addr_end(addr, end);
if (pud_none_or_clear_bad(pud)) {
if (walk->pte_hole)
- err = walk->pte_hole(addr, next, private);
+ err = walk->pte_hole(addr, next, walk);
if (err)
break;
continue;
}
if (walk->pud_entry)
- err = walk->pud_entry(pud, addr, next, private);
+ err = walk->pud_entry(pud, addr, next, walk);
if (!err && (walk->pmd_entry || walk->pte_entry))
- err = walk_pmd_range(pud, addr, next, walk, private);
+ err = walk_pmd_range(pud, addr, next, walk);
if (err)
break;
} while (pud++, addr = next, addr != end);
@@ -85,15 +85,15 @@ static int walk_pud_range(pgd_t *pgd, un
* @addr: starting address
* @end: ending address
* @walk: set of callbacks to invoke for each level of the tree
- * @private: private data passed to the callback function
*
* Recursively walk the page table for the memory area in a VMA,
* calling supplied callbacks. Callbacks are called in-order (first
* PGD, first PUD, first PMD, first PTE, second PTE... second PMD,
* etc.). If lower-level callbacks are omitted, walking depth is reduced.
*
- * Each callback receives an entry pointer, the start and end of the
- * associated range, and a caller-supplied private data pointer.
+ * Each callback receives an entry pointer and the start and end of the
+ * associated range, and a copy of the original mm_walk for access to
+ * the ->private or ->mm fields.
*
* No locks are taken, but the bottom level iterator will map PTE
* directories from highmem if necessary.
@@ -101,9 +101,8 @@ static int walk_pud_range(pgd_t *pgd, un
* If any callback returns a non-zero value, the walk is aborted and
* the return value is propagated back to the caller. Otherwise 0 is returned.
*/
-int walk_page_range(const struct mm_struct *mm,
- unsigned long addr, unsigned long end,
- const struct mm_walk *walk, void *private)
+int walk_page_range(unsigned long addr, unsigned long end,
+ struct mm_walk *walk)
{
pgd_t *pgd;
unsigned long next;
@@ -112,21 +111,23 @@ int walk_page_range(const struct mm_stru
if (addr >= end)
return err;
- pgd = pgd_offset(mm, addr);
+ if (!walk->mm)
+ return -EINVAL;
+ pgd = pgd_offset(walk->mm, addr);
do {
next = pgd_addr_end(addr, end);
if (pgd_none_or_clear_bad(pgd)) {
if (walk->pte_hole)
- err = walk->pte_hole(addr, next, private);
+ err = walk->pte_hole(addr, next, walk);
if (err)
break;
continue;
}
if (walk->pgd_entry)
- err = walk->pgd_entry(pgd, addr, next, private);
+ err = walk->pgd_entry(pgd, addr, next, walk);
if (!err &&
(walk->pud_entry || walk->pmd_entry || walk->pte_entry))
- err = walk_pud_range(pgd, addr, next, walk, private);
+ err = walk_pud_range(pgd, addr, next, walk);
if (err)
break;
} while (pgd++, addr = next, addr != end);
diff -puN include/linux/mm.h~pass-mm-into-pagewalkers include/linux/mm.h
--- linux-2.6.git/include/linux/mm.h~pass-mm-into-pagewalkers 2008-05-08 15:49:47.000000000 -0700
+++ linux-2.6.git-dave/include/linux/mm.h 2008-05-08 15:49:54.000000000 -0700
@@ -760,16 +760,17 @@ unsigned long unmap_vmas(struct mmu_gath
* (see walk_page_range for more details)
*/
struct mm_walk {
- int (*pgd_entry)(pgd_t *, unsigned long, unsigned long, void *);
- int (*pud_entry)(pud_t *, unsigned long, unsigned long, void *);
- int (*pmd_entry)(pmd_t *, unsigned long, unsigned long, void *);
- int (*pte_entry)(pte_t *, unsigned long, unsigned long, void *);
- int (*pte_hole)(unsigned long, unsigned long, void *);
+ int (*pgd_entry)(pgd_t *, unsigned long, unsigned long, struct mm_walk *);
+ int (*pud_entry)(pud_t *, unsigned long, unsigned long, struct mm_walk *);
+ int (*pmd_entry)(pmd_t *, unsigned long, unsigned long, struct mm_walk *);
+ int (*pte_entry)(pte_t *, unsigned long, unsigned long, struct mm_walk *);
+ int (*pte_hole)(unsigned long, unsigned long, struct mm_walk *);
+ struct mm_struct *mm;
+ void *private;
};
-int walk_page_range(const struct mm_struct *, unsigned long addr,
- unsigned long end, const struct mm_walk *walk,
- void *private);
+int walk_page_range(unsigned long addr, unsigned long end,
+ struct mm_walk *walk);
void free_pgd_range(struct mmu_gather **tlb, unsigned long addr,
unsigned long end, unsigned long floor, unsigned long ceiling);
void free_pgtables(struct mmu_gather **tlb, struct vm_area_struct *start_vma,
diff -puN fs/proc/task_mmu.c~pass-mm-into-pagewalkers fs/proc/task_mmu.c
--- linux-2.6.git/fs/proc/task_mmu.c~pass-mm-into-pagewalkers 2008-05-08 15:49:47.000000000 -0700
+++ linux-2.6.git-dave/fs/proc/task_mmu.c 2008-05-08 15:49:59.000000000 -0700
@@ -317,9 +317,9 @@ struct mem_size_stats {
};
static int smaps_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end,
- void *private)
+ struct mm_walk *walk)
{
- struct mem_size_stats *mss = private;
+ struct mem_size_stats *mss = walk->private;
struct vm_area_struct *vma = mss->vma;
pte_t *pte, ptent;
spinlock_t *ptl;
@@ -367,19 +367,22 @@ static int smaps_pte_range(pmd_t *pmd, u
return 0;
}
-static struct mm_walk smaps_walk = { .pmd_entry = smaps_pte_range };
-
static int show_smap(struct seq_file *m, void *v)
{
struct vm_area_struct *vma = v;
struct mem_size_stats mss;
int ret;
+ struct mm_walk smaps_walk = {
+ .pmd_entry = smaps_pte_range,
+ .mm = vma->vm_mm,
+ .private = &mss,
+ };
+
memset(&mss, 0, sizeof mss);
mss.vma = vma;
if (vma->vm_mm && !is_vm_hugetlb_page(vma))
- walk_page_range(vma->vm_mm, vma->vm_start, vma->vm_end,
- &smaps_walk, &mss);
+ walk_page_range(vma->vm_start, vma->vm_end, &smaps_walk);
ret = show_map(m, v);
if (ret)
@@ -428,9 +431,9 @@ const struct file_operations proc_smaps_
};
static int clear_refs_pte_range(pmd_t *pmd, unsigned long addr,
- unsigned long end, void *private)
+ unsigned long end, struct mm_walk *walk)
{
- struct vm_area_struct *vma = private;
+ struct vm_area_struct *vma = walk->private;
pte_t *pte, ptent;
spinlock_t *ptl;
struct page *page;
@@ -454,8 +457,6 @@ static int clear_refs_pte_range(pmd_t *p
return 0;
}
-static struct mm_walk clear_refs_walk = { .pmd_entry = clear_refs_pte_range };
-
static ssize_t clear_refs_write(struct file *file, const char __user *buf,
size_t count, loff_t *ppos)
{
@@ -478,11 +479,17 @@ static ssize_t clear_refs_write(struct f
return -ESRCH;
mm = get_task_mm(task);
if (mm) {
+ static struct mm_walk clear_refs_walk;
+ memset(&clear_refs_walk, 0, sizeof(clear_refs_walk));
+ clear_refs_walk.pmd_entry = clear_refs_pte_range;
+ clear_refs_walk.mm = mm;
down_read(&mm->mmap_sem);
- for (vma = mm->mmap; vma; vma = vma->vm_next)
+ for (vma = mm->mmap; vma; vma = vma->vm_next) {
+ clear_refs_walk.private = vma;
if (!is_vm_hugetlb_page(vma))
- walk_page_range(mm, vma->vm_start, vma->vm_end,
- &clear_refs_walk, vma);
+ walk_page_range(vma->vm_start, vma->vm_end,
+ &clear_refs_walk);
+ }
flush_tlb_mm(mm);
up_read(&mm->mmap_sem);
mmput(mm);
@@ -540,9 +547,9 @@ static int add_to_pagemap(unsigned long
}
static int pagemap_pte_hole(unsigned long start, unsigned long end,
- void *private)
+ struct mm_walk *walk)
{
- struct pagemapread *pm = private;
+ struct pagemapread *pm = walk->private;
unsigned long addr;
int err = 0;
for (addr = start; addr < end; addr += PAGE_SIZE) {
@@ -560,9 +567,9 @@ static u64 swap_pte_to_pagemap_entry(pte
}
static int pagemap_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end,
- void *private)
+ struct mm_walk *walk)
{
- struct pagemapread *pm = private;
+ struct pagemapread *pm = walk->private;
pte_t *pte;
int err = 0;
@@ -687,8 +694,8 @@ static ssize_t pagemap_read(struct file
* user buffer is tracked in "pm", and the walk
* will stop when we hit the end of the buffer.
*/
- ret = walk_page_range(mm, start_vaddr, end_vaddr,
- &pagemap_walk, &pm);
+ ret = walk_page_range(start_vaddr, end_vaddr,
+ &pagemap_walk);
if (ret == PM_END_OF_BUFFER)
ret = 0;
/* don't need mmap_sem for these, but this looks cleaner */
_
-- Dave
--
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