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Subject[RFC 05/11] mm: debug: dump page into a string rather than directly on screen
Date
This lets us use regular string formatting code to dump VMAs, use it
in VM_BUG_ON_PAGE instead of just printing it to screen as well.

Signed-off-by: Sasha Levin <sasha.levin@oracle.com>
---
include/linux/mmdebug.h | 6 ++----
lib/vsprintf.c | 5 ++++-
mm/balloon_compaction.c | 4 ++--
mm/debug.c | 28 +++++++++++-----------------
mm/kasan/report.c | 2 +-
mm/memory.c | 2 +-
mm/memory_hotplug.c | 2 +-
mm/page_alloc.c | 2 +-
8 files changed, 23 insertions(+), 28 deletions(-)

diff --git a/include/linux/mmdebug.h b/include/linux/mmdebug.h
index 202ebdf..8b3f5a0 100644
--- a/include/linux/mmdebug.h
+++ b/include/linux/mmdebug.h
@@ -7,9 +7,7 @@ struct page;
struct vm_area_struct;
struct mm_struct;

-extern void dump_page(struct page *page, const char *reason);
-extern void dump_page_badflags(struct page *page, const char *reason,
- unsigned long badflags);
+char *format_page(struct page *page, char *buf, char *end);

#ifdef CONFIG_DEBUG_VM
char *format_vma(const struct vm_area_struct *vma, char *buf, char *end);
@@ -18,7 +16,7 @@ char *format_mm(const struct mm_struct *mm, char *buf, char *end);
#define VM_BUG_ON_PAGE(cond, page) \
do { \
if (unlikely(cond)) { \
- dump_page(page, "VM_BUG_ON_PAGE(" __stringify(cond)")");\
+ pr_emerg("%pZp", page); \
BUG(); \
} \
} while (0)
diff --git a/lib/vsprintf.c b/lib/vsprintf.c
index 1ca3114..8511be7 100644
--- a/lib/vsprintf.c
+++ b/lib/vsprintf.c
@@ -1384,6 +1384,8 @@ char *mm_pointer(char *buf, char *end, const void *ptr,
return format_vma(ptr, buf, end);
case 'm':
return format_mm(ptr, buf, end);
+ case 'p':
+ return format_page(ptr, buf, end);
}

return buf;
@@ -1477,9 +1479,10 @@ int kptr_restrict __read_mostly;
* (legacy clock framework) of the clock
* - 'Cr' For a clock, it prints the current rate of the clock
* - 'T' task_struct->comm
- * - 'Z[mv]' Outputs a readable version of a type of memory management struct:
+ * - 'Z[mpv]' Outputs a readable version of a type of memory management struct:
* v struct vm_area_struct
* m struct mm_struct
+ * p struct page
*
* Note: The difference between 'S' and 'F' is that on ia64 and ppc64
* function pointers are really function descriptors, which contain a
diff --git a/mm/balloon_compaction.c b/mm/balloon_compaction.c
index fcad832..88b3cae 100644
--- a/mm/balloon_compaction.c
+++ b/mm/balloon_compaction.c
@@ -187,7 +187,7 @@ void balloon_page_putback(struct page *page)
put_page(page);
} else {
WARN_ON(1);
- dump_page(page, "not movable balloon page");
+ pr_alert("Not movable balloon page:\n%pZp", page);
}
unlock_page(page);
}
@@ -207,7 +207,7 @@ int balloon_page_migrate(struct page *newpage,
BUG_ON(!trylock_page(newpage));

if (WARN_ON(!__is_movable_balloon_page(page))) {
- dump_page(page, "not movable balloon page");
+ pr_alert("Not movable balloon page:\n%pZp", page);
unlock_page(newpage);
return rc;
}
diff --git a/mm/debug.c b/mm/debug.c
index dff65ff..f64bb6e 100644
--- a/mm/debug.c
+++ b/mm/debug.c
@@ -115,32 +115,26 @@ static char *format_flags(unsigned long flags,
return buf;
}

-void dump_page_badflags(struct page *page, const char *reason,
- unsigned long badflags)
+char *format_page(struct page *page, char *buf, char *end)
{
- pr_emerg("page:%p count:%d mapcount:%d mapping:%p index:%#lx\n",
+ buf += snprintf(buf, (buf > end ? 0 : end - buf),
+ "page:%p count:%d mapcount:%d mapping:%p index:%#lx\n",
page, atomic_read(&page->_count), page_mapcount(page),
page->mapping, page->index);
+
BUILD_BUG_ON(ARRAY_SIZE(pageflag_names) != __NR_PAGEFLAGS);
- dump_flags(page->flags, pageflag_names, ARRAY_SIZE(pageflag_names));
- if (reason)
- pr_alert("page dumped because: %s\n", reason);
- if (page->flags & badflags) {
- pr_alert("bad because of flags:\n");
- dump_flags(page->flags & badflags,
- pageflag_names, ARRAY_SIZE(pageflag_names));
- }
+
+ buf = format_flags(page->flags, pageflag_names,
+ ARRAY_SIZE(pageflag_names), buf, end);
#ifdef CONFIG_MEMCG
if (page->mem_cgroup)
- pr_alert("page->mem_cgroup:%p\n", page->mem_cgroup);
+ buf += snprintf(buf, (buf > end ? 0 : end - buf),
+ "page->mem_cgroup:%p\n", page->mem_cgroup);
#endif
-}

-void dump_page(struct page *page, const char *reason)
-{
- dump_page_badflags(page, reason, 0);
+ return buf;
}
-EXPORT_SYMBOL(dump_page);
+EXPORT_SYMBOL(format_page);

#ifdef CONFIG_DEBUG_VM

diff --git a/mm/kasan/report.c b/mm/kasan/report.c
index 680ceed..272a282 100644
--- a/mm/kasan/report.c
+++ b/mm/kasan/report.c
@@ -121,7 +121,7 @@ static void print_address_description(struct kasan_access_info *info)
"kasan: bad access detected");
return;
}
- dump_page(page, "kasan: bad access detected");
+ pr_emerg("kasan: bad access detected:\n%pZp", page);
}

if (kernel_or_module_addr(addr)) {
diff --git a/mm/memory.c b/mm/memory.c
index d1fa0c1..6e5d4bd 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -683,7 +683,7 @@ static void print_bad_pte(struct vm_area_struct *vma, unsigned long addr,
current->comm,
(long long)pte_val(pte), (long long)pmd_val(*pmd));
if (page)
- dump_page(page, "bad pte");
+ pr_alert("Bad pte:\n%pZp", page);
printk(KERN_ALERT
"addr:%p vm_flags:%08lx anon_vma:%p mapping:%p index:%lx\n",
(void *)addr, vma->vm_flags, vma->anon_vma, mapping, index);
diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index c6a8d95..366fba0 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -1431,7 +1431,7 @@ do_migrate_range(unsigned long start_pfn, unsigned long end_pfn)
#ifdef CONFIG_DEBUG_VM
printk(KERN_ALERT "removing pfn %lx from LRU failed\n",
pfn);
- dump_page(page, "failed to remove from LRU");
+ pr_alert("Failed to remove from LRU:\n%pZp", page);
#endif
put_page(page);
/* Because we don't have big zone->lock. we should
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 5bd9711..4887731 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -332,7 +332,7 @@ static void bad_page(struct page *page, const char *reason,

printk(KERN_ALERT "BUG: Bad page state in process %s pfn:%05lx\n",
current->comm, page_to_pfn(page));
- dump_page_badflags(page, reason, bad_flags);
+ pr_alert("%s:\n%pZpBad flags: %lX", reason, page, bad_flags);

print_modules();
dump_stack();
--
1.7.10.4


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