Re: THP bug and crash on sparc64 3.8

From: David Miller
Date: Tue Feb 19 2013 - 14:33:29 EST


From: Meelis Roos <mroos@xxxxx>
Date: Tue, 19 Feb 2013 14:05:42 +0200 (EET)

>> Call Trace:
>> [0000000000488d9c] __might_sleep+0x13c/0x240
>> [000000000051204c] kmem_cache_alloc+0xcc/0x120
>> [000000000044bfc0] tsb_grow+0x80/0x480
>> [000000000044e814] hugetlb_setup+0x14/0xc0
>> [000000000044bcb0] set_pmd_at+0x110/0x120
>> [00000000005170b8] khugepaged+0xd78/0xf80
>> [000000000047e508] kthread+0x88/0xa0
>> [00000000004060a4] ret_from_syscall+0x1c/0x2c
>> [0000000000000000] (null)

First, thanks for (unlike me) testing with CONFIG_DEBUG_ATOMIC_SLEEP.

I'm testing the following patch and if you would do so as well I'd
appreciate it.

Thanks!

diff --git a/arch/sparc/include/asm/hugetlb.h b/arch/sparc/include/asm/hugetlb.h
index 9661e9b..d49dc54 100644
--- a/arch/sparc/include/asm/hugetlb.h
+++ b/arch/sparc/include/asm/hugetlb.h
@@ -12,7 +12,7 @@ pte_t huge_ptep_get_and_clear(struct mm_struct *mm, unsigned long addr,

static inline void hugetlb_prefault_arch_hook(struct mm_struct *mm)
{
- hugetlb_setup(mm);
+ hugetlb_setup(mm, GFP_KERNEL);
}

static inline int is_hugepage_only_range(struct mm_struct *mm,
diff --git a/arch/sparc/include/asm/mmu_context_64.h b/arch/sparc/include/asm/mmu_context_64.h
index 9191ca6..fd6786f8 100644
--- a/arch/sparc/include/asm/mmu_context_64.h
+++ b/arch/sparc/include/asm/mmu_context_64.h
@@ -46,7 +46,7 @@ static inline void tsb_context_switch(struct mm_struct *mm)
, __pa(&mm->context.tsb_descr[0]));
}

-extern void tsb_grow(struct mm_struct *mm, unsigned long tsb_index, unsigned long mm_rss);
+extern void tsb_grow(struct mm_struct *mm, unsigned long tsb_index, unsigned long mm_rss, gfp_t gfp);
#ifdef CONFIG_SMP
extern void smp_tsb_sync(struct mm_struct *mm);
#else
diff --git a/arch/sparc/include/asm/page_64.h b/arch/sparc/include/asm/page_64.h
index 4b39f74..f97ee3b 100644
--- a/arch/sparc/include/asm/page_64.h
+++ b/arch/sparc/include/asm/page_64.h
@@ -28,7 +28,7 @@

#if defined(CONFIG_HUGETLB_PAGE) || defined(CONFIG_TRANSPARENT_HUGEPAGE)
struct mm_struct;
-extern void hugetlb_setup(struct mm_struct *mm);
+extern void hugetlb_setup(struct mm_struct *mm, gfp_t gfp);
#endif

#define WANT_PAGE_VIRTUAL
diff --git a/arch/sparc/mm/fault_64.c b/arch/sparc/mm/fault_64.c
index 097aee7..0852d98 100644
--- a/arch/sparc/mm/fault_64.c
+++ b/arch/sparc/mm/fault_64.c
@@ -468,12 +468,12 @@ good_area:
#endif
if (unlikely(mm_rss >
mm->context.tsb_block[MM_TSB_BASE].tsb_rss_limit))
- tsb_grow(mm, MM_TSB_BASE, mm_rss);
+ tsb_grow(mm, MM_TSB_BASE, mm_rss, GFP_KERNEL);
#if defined(CONFIG_HUGETLB_PAGE) || defined(CONFIG_TRANSPARENT_HUGEPAGE)
mm_rss = mm->context.huge_pte_count;
if (unlikely(mm_rss >
mm->context.tsb_block[MM_TSB_HUGE].tsb_rss_limit))
- tsb_grow(mm, MM_TSB_HUGE, mm_rss);
+ tsb_grow(mm, MM_TSB_HUGE, mm_rss, GFP_KERNEL);
#endif
return;

diff --git a/arch/sparc/mm/init_64.c b/arch/sparc/mm/init_64.c
index c3b7242..0c23fa1 100644
--- a/arch/sparc/mm/init_64.c
+++ b/arch/sparc/mm/init_64.c
@@ -2712,16 +2712,18 @@ static void context_reload(void *__data)
load_secondary_context(mm);
}

-void hugetlb_setup(struct mm_struct *mm)
+void hugetlb_setup(struct mm_struct *mm, gfp_t gfp)
{
struct tsb_config *tp = &mm->context.tsb_block[MM_TSB_HUGE];

if (likely(tp->tsb != NULL))
return;

- tsb_grow(mm, MM_TSB_HUGE, 0);
- tsb_context_switch(mm);
- smp_tsb_sync(mm);
+ tsb_grow(mm, MM_TSB_HUGE, 0, gfp);
+ if (tp->tsb != NULL) {
+ tsb_context_switch(mm);
+ smp_tsb_sync(mm);
+ }

/* On UltraSPARC-III+ and later, configure the second half of
* the Data-TLB for huge pages.
diff --git a/arch/sparc/mm/tlb.c b/arch/sparc/mm/tlb.c
index 3e8fec3..de51c40 100644
--- a/arch/sparc/mm/tlb.c
+++ b/arch/sparc/mm/tlb.c
@@ -136,7 +136,7 @@ void set_pmd_at(struct mm_struct *mm, unsigned long addr,
else
mm->context.huge_pte_count--;
if (mm->context.huge_pte_count == 1)
- hugetlb_setup(mm);
+ hugetlb_setup(mm, GFP_ATOMIC);
}

if (!pmd_none(orig)) {
diff --git a/arch/sparc/mm/tsb.c b/arch/sparc/mm/tsb.c
index 7f64743..338b406 100644
--- a/arch/sparc/mm/tsb.c
+++ b/arch/sparc/mm/tsb.c
@@ -288,14 +288,13 @@ static unsigned long tsb_size_to_rss_limit(unsigned long new_size)
* the number of entries that the current TSB can hold at once. Currently,
* we trigger when the RSS hits 3/4 of the TSB capacity.
*/
-void tsb_grow(struct mm_struct *mm, unsigned long tsb_index, unsigned long rss)
+void tsb_grow(struct mm_struct *mm, unsigned long tsb_index, unsigned long rss, gfp_t gfp)
{
unsigned long max_tsb_size = 1 * 1024 * 1024;
unsigned long new_size, old_size, flags;
struct tsb *old_tsb, *new_tsb;
unsigned long new_cache_index, old_cache_index;
unsigned long new_rss_limit;
- gfp_t gfp_flags;

if (max_tsb_size > (PAGE_SIZE << MAX_ORDER))
max_tsb_size = (PAGE_SIZE << MAX_ORDER);
@@ -312,12 +311,11 @@ void tsb_grow(struct mm_struct *mm, unsigned long tsb_index, unsigned long rss)
new_rss_limit = ~0UL;

retry_tsb_alloc:
- gfp_flags = GFP_KERNEL;
if (new_size > (PAGE_SIZE * 2))
- gfp_flags = __GFP_NOWARN | __GFP_NORETRY;
+ gfp = __GFP_NOWARN | __GFP_NORETRY;

new_tsb = kmem_cache_alloc_node(tsb_caches[new_cache_index],
- gfp_flags, numa_node_id());
+ gfp, numa_node_id());
if (unlikely(!new_tsb)) {
/* Not being able to fork due to a high-order TSB
* allocation failure is very bad behavior. Just back
@@ -457,11 +455,11 @@ int init_new_context(struct task_struct *tsk, struct mm_struct *mm)
/* If this is fork, inherit the parent's TSB size. We would
* grow it to that size on the first page fault anyways.
*/
- tsb_grow(mm, MM_TSB_BASE, get_mm_rss(mm));
+ tsb_grow(mm, MM_TSB_BASE, get_mm_rss(mm), GFP_KERNEL);

#if defined(CONFIG_HUGETLB_PAGE) || defined(CONFIG_TRANSPARENT_HUGEPAGE)
if (unlikely(huge_pte_count))
- tsb_grow(mm, MM_TSB_HUGE, huge_pte_count);
+ tsb_grow(mm, MM_TSB_HUGE, huge_pte_count, GFP_KERNEL);
#endif

if (unlikely(!mm->context.tsb_block[MM_TSB_BASE].tsb))
--
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