"Aneesh Kumar K.V" <aneesh.ku...@linux.vnet.ibm.com> writes:
> Benjamin Herrenschmidt <b...@au1.ibm.com> writes:
>
>> On Wed, 2013-05-29 at 22:47 -0700, Hugh Dickins wrote:
>>> Running my favourite swapping load (repeated make -j20 kernel builds
>>> in tmpfs in parallel with repeated make -j20 kernel builds in ext4 on
>>> loop on tmpfs file, all limited by mem=700M and swap 1.5G) on 3.10-rc
>>> on PowerMac G5, the test dies with corrupted usermem after a few hours.
>>>
>>> Variously, segmentation fault or Binutils assertion fail or gcc Internal
>>> error in either or both builds: usually signs of swapping or TLB flushing
>>> gone wrong. Sometimes the tmpfs build breaks first, sometimes the ext4 on
>>> loop on tmpfs, so at least it looks unrelated to loop. No problem on x86.
>>>
>>> This is 64-bit kernel but 4k pages and old SuSE 11.1 32-bit userspace.
>>>
>>> I've just finished a manual bisection on arch/powerpc/mm (which might
>>> have been a wrong guess, but has paid off): the first bad commit is
>>> 7e74c3921ad9610c0b49f28b8fc69f7480505841
>>> "powerpc: Fix hpte_decode to use the correct decoding for page sizes".
>>
>> Ok, I have other reasons to think is wrong. I debugged a case last week
>> where after kexec we still had stale TLB entries, due to the TLB cleanup
>> not working.
>>
>> Thanks for doing that bisection ! I'll investigate ASAP (though it will
>> probably have to wait for tomorrow unless Paul beats me to it)
>>
>>> I don't know if it's actually swapping to swap that's triggering the
>>> problem, or a more general page reclaim or TLB flush problem. I hit
>>> it originally when trying to test Mel Gorman's pagevec series on top
>>> of 3.10-rc; and though I then reproduced it without that series, it
>>> did seem to take much longer: so I have been applying Mel's series to
>>> speed up each step of the bisection. But if I went back again, might
>>> find it was just chance that I hit it sooner with Mel's series than
>>> without. So, you're probably safe to ignore that detail, but I
>>> mention it just in case it turns out to have some relevance.
>>>
>>> Something else peculiar that I've been doing in these runs, may or may
>>> not be relevant: I've been running swapon and swapoff repeatedly in the
>>> background, so that we're doing swapoff even while busy building.
>>>
>>> I probably can't go into much more detail on the test (it's hard
>>> to get the balance right, to be swapping rather than OOMing or just
>>> running without reclaim), but can test any patches you'd like me to
>>> try (though it may take 24 hours for me to report back usefully).
>>
>> I think it's just failing to invalidate the TLB properly. At least one
>> bug I can spot just looking at it:
>>
>> static void native_hpte_invalidate(unsigned long slot, unsigned long vpn,
>> int psize, int ssize, int local)
>>
>> .../...
>>
>> native_lock_hpte(hptep);
>> hpte_v = hptep->v;
>>
>> actual_psize = hpte_actual_psize(hptep, psize);
>> if (actual_psize < 0) {
>> native_unlock_hpte(hptep);
>> local_irq_restore(flags);
>> return;
>> }
>>
>> That's wrong. We must still perform the TLB invalidation even if the
>> hash PTE is empty.
>>
>> In fact, Aneesh, this is a problem with MPSS for your THP work, I just
>> thought about it.
>>
>> The reason is that if a hash bucket gets full, we "evict" a more/less
>> random entry from it. When we do that we don't invalidate the TLB
>> (hpte_remove) because we assume the old translation is still technically
>> "valid".
>>
>
> Hmm that is correct, I missed that. But to do a tlb invalidate we need
> both base and actual page size. One of the reason i didn't update the
> hpte_invalidate callback to take both the page sizes was because, PAPR
> didn't need that for invalidate (H_REMOVE). hpte_remove did result in a
> tlb invalidate there.
>
>
>> However that means that an hpte_invalidate *must* invalidate the TLB
>> later on even if it's not hitting the right entry in the hash.
>>
>> However, I can see why that cannot work with THP/MPSS since you have no
>> way to know the page size from the PTE anymore....
>>
>> So my question is, apart from hpte_decode used by kexec, which I will
>> fix by just blowing the whole TLB when not running phyp, why do you need
>> the "actual" size in invalidate and updatepp ? You really can't rely on
>> the size passed by the upper layers ?
>
> So for upstream I have below which should address the
> above. Meanwhile I will see what the impact would be to do a tlb
> invalidate in hpte_remove, so that we can keep both lpar and native
> changes similar.
>
How about the below ?
commit 9f70fd8cfeb7fca33ef8453197b76df46c860b52
Author: Aneesh Kumar K.V <aneesh.ku...@linux.vnet.ibm.com>
Date: Thu May 30 20:09:58 2013 +0530
powerpc/mm: Always invalidate tlb on hpte invalidate and update
If a hash bucket gets full, we "evict" a more/less random entry from it.
When we do that we don't invalidate the TLB (hpte_remove) because we assume
the old translation is still technically "valid". This implies that when
we are invalidating or updating pte, even if HPTE entry is not valid
we should do a tlb invalidate.
Signed-off-by: Aneesh Kumar K.V <aneesh.ku...@linux.vnet.ibm.com>
diff --git a/arch/powerpc/include/asm/machdep.h
b/arch/powerpc/include/asm/machdep.h
index 92386fc..801e3c6 100644
--- a/arch/powerpc/include/asm/machdep.h
+++ b/arch/powerpc/include/asm/machdep.h
@@ -36,13 +36,13 @@ struct machdep_calls {
#ifdef CONFIG_PPC64
void (*hpte_invalidate)(unsigned long slot,
unsigned long vpn,
- int psize, int ssize,
- int local);
+ int bpsize, int apsize,
+ int ssize, int local);
long (*hpte_updatepp)(unsigned long slot,
unsigned long newpp,
unsigned long vpn,
- int psize, int ssize,
- int local);
+ int bpsize, int apsize,
+ int ssize, int local);
void (*hpte_updateboltedpp)(unsigned long newpp,
unsigned long ea,
int psize, int ssize);
diff --git a/arch/powerpc/kvm/book3s_64_mmu_host.c
b/arch/powerpc/kvm/book3s_64_mmu_host.c
index 3a9a1ac..176d3fd 100644
--- a/arch/powerpc/kvm/book3s_64_mmu_host.c
+++ b/arch/powerpc/kvm/book3s_64_mmu_host.c
@@ -34,7 +34,7 @@
void kvmppc_mmu_invalidate_pte(struct kvm_vcpu *vcpu, struct hpte_cache *pte)
{
ppc_md.hpte_invalidate(pte->slot, pte->host_vpn,
- MMU_PAGE_4K, MMU_SEGSIZE_256M,
+ MMU_PAGE_4K, MMU_PAGE_4K, MMU_SEGSIZE_256M,
false);
}
diff --git a/arch/powerpc/mm/hash_low_64.S b/arch/powerpc/mm/hash_low_64.S
index 0e980ac..d3cbda6 100644
--- a/arch/powerpc/mm/hash_low_64.S
+++ b/arch/powerpc/mm/hash_low_64.S
@@ -289,9 +289,10 @@ htab_modify_pte:
/* Call ppc_md.hpte_updatepp */
mr r5,r29 /* vpn */
- li r6,MMU_PAGE_4K /* page size */
- ld r7,STK_PARAM(R9)(r1) /* segment size */
- ld r8,STK_PARAM(R8)(r1) /* get "local" param */
+ li r6,MMU_PAGE_4K /* base page size */
+ li r7,MMU_PAGE_4K /* actual page size */
+ ld r8,STK_PARAM(R9)(r1) /* segment size */
+ ld r9,STK_PARAM(R8)(r1) /* get "local" param */
_GLOBAL(htab_call_hpte_updatepp)
bl . /* Patched by htab_finish_init() */
@@ -649,9 +650,10 @@ htab_modify_pte:
/* Call ppc_md.hpte_updatepp */
mr r5,r29 /* vpn */
- li r6,MMU_PAGE_4K /* page size */
- ld r7,STK_PARAM(R9)(r1) /* segment size */
- ld r8,STK_PARAM(R8)(r1) /* get "local" param */
+ li r6,MMU_PAGE_4K /* base page size */
+ li r7,MMU_PAGE_4K /* actual page size */
+ ld r8,STK_PARAM(R9)(r1) /* segment size */
+ ld r9,STK_PARAM(R8)(r1) /* get "local" param */
_GLOBAL(htab_call_hpte_updatepp)
bl . /* patched by htab_finish_init() */
@@ -937,9 +939,10 @@ ht64_modify_pte:
/* Call ppc_md.hpte_updatepp */
mr r5,r29 /* vpn */
- li r6,MMU_PAGE_64K
- ld r7,STK_PARAM(R9)(r1) /* segment size */
- ld r8,STK_PARAM(R8)(r1) /* get "local" param */
+ li r6,MMU_PAGE_64K /* base page size */
+ li r7,MMU_PAGE_64K /* actual page size */
+ ld r8,STK_PARAM(R9)(r1) /* segment size */
+ ld r9,STK_PARAM(R8)(r1) /* get "local" param */
_GLOBAL(ht64_call_hpte_updatepp)
bl . /* patched by htab_finish_init() */
diff --git a/arch/powerpc/mm/hash_native_64.c b/arch/powerpc/mm/hash_native_64.c
index 6a2aead..121c8ef 100644
--- a/arch/powerpc/mm/hash_native_64.c
+++ b/arch/powerpc/mm/hash_native_64.c
@@ -273,61 +273,15 @@ static long native_hpte_remove(unsigned long hpte_group)
return i;
}
-static inline int __hpte_actual_psize(unsigned int lp, int psize)
-{
- int i, shift;
- unsigned int mask;
-
- /* start from 1 ignoring MMU_PAGE_4K */
- for (i = 1; i < MMU_PAGE_COUNT; i++) {
-
- /* invalid penc */
- if (mmu_psize_defs[psize].penc[i] == -1)
- continue;
- /*
- * encoding bits per actual page size
- * PTE LP actual page size
- * rrrr rrrz >=8KB
- * rrrr rrzz >=16KB
- * rrrr rzzz >=32KB
- * rrrr zzzz >=64KB
- * .......
- */
- shift = mmu_psize_defs[i].shift - LP_SHIFT;
- if (shift > LP_BITS)
- shift = LP_BITS;
- mask = (1 << shift) - 1;
- if ((lp & mask) == mmu_psize_defs[psize].penc[i])
- return i;
- }
- return -1;
-}
-
-static inline int hpte_actual_psize(struct hash_pte *hptep, int psize)
-{
- /* Look at the 8 bit LP value */
- unsigned int lp = (hptep->r >> LP_SHIFT) & ((1 << LP_BITS) - 1);
-
- if (!(hptep->v & HPTE_V_VALID))
- return -1;
-
- /* First check if it is large page */
- if (!(hptep->v & HPTE_V_LARGE))
- return MMU_PAGE_4K;
-
- return __hpte_actual_psize(lp, psize);
-}
-
static long native_hpte_updatepp(unsigned long slot, unsigned long newpp,
- unsigned long vpn, int psize, int ssize,
- int local)
+ unsigned long vpn, int bpsize,
+ int apsize, int ssize, int local)
{
struct hash_pte *hptep = htab_address + slot;
unsigned long hpte_v, want_v;
int ret = 0;
- int actual_psize;
- want_v = hpte_encode_avpn(vpn, psize, ssize);
+ want_v = hpte_encode_avpn(vpn, bpsize, ssize);
DBG_LOW(" update(vpn=%016lx, avpnv=%016lx, group=%lx, newpp=%lx)",
vpn, want_v & HPTE_V_AVPN, slot, newpp);
@@ -335,13 +289,14 @@ static long native_hpte_updatepp(unsigned long slot,
unsigned long newpp,
native_lock_hpte(hptep);
hpte_v = hptep->v;
- actual_psize = hpte_actual_psize(hptep, psize);
- if (actual_psize < 0) {
- native_unlock_hpte(hptep);
- return -1;
- }
- /* Even if we miss, we need to invalidate the TLB */
- if (!HPTE_V_COMPARE(hpte_v, want_v)) {
+ /*
+ * We need to invalidate the TLB always because hpte_remove doesn't do
+ * a tlb invalidate. If a hash bucket gets full, we "evict" a more/less
+ * random entry from it. When we do that we don't invalidate the TLB
+ * (hpte_remove) because we assume the old translation is still
technically
+ * "valid".
+ */
+ if (!HPTE_V_COMPARE(hpte_v, want_v) || !(hpte_v & HPTE_V_VALID)) {
DBG_LOW(" -> miss\n");
ret = -1;
} else {
@@ -353,7 +308,7 @@ static long native_hpte_updatepp(unsigned long slot,
unsigned long newpp,
native_unlock_hpte(hptep);
/* Ensure it is out of the tlb too. */
- tlbie(vpn, psize, actual_psize, ssize, local);
+ tlbie(vpn, bpsize, apsize, ssize, local);
return ret;
}
@@ -394,7 +349,6 @@ static long native_hpte_find(unsigned long vpn, int psize,
int ssize)
static void native_hpte_updateboltedpp(unsigned long newpp, unsigned long ea,
int psize, int ssize)
{
- int actual_psize;
unsigned long vpn;
unsigned long vsid;
long slot;
@@ -407,54 +361,82 @@ static void native_hpte_updateboltedpp(unsigned long
newpp, unsigned long ea,
if (slot == -1)
panic("could not find page to bolt\n");
hptep = htab_address + slot;
- actual_psize = hpte_actual_psize(hptep, psize);
- if (actual_psize < 0)
- return;
/* Update the HPTE */
hptep->r = (hptep->r & ~(HPTE_R_PP | HPTE_R_N)) |
(newpp & (HPTE_R_PP | HPTE_R_N));
-
- /* Ensure it is out of the tlb too. */
- tlbie(vpn, psize, actual_psize, ssize, 0);
+ /*
+ * Ensure it is out of the tlb too. Bolted entries base and
+ * actual page size will be same.
+ */
+ tlbie(vpn, psize, psize, ssize, 0);
}
static void native_hpte_invalidate(unsigned long slot, unsigned long vpn,
- int psize, int ssize, int local)
+ int bpsize, int apsize, int ssize, int local)
{
struct hash_pte *hptep = htab_address + slot;
unsigned long hpte_v;
unsigned long want_v;
unsigned long flags;
- int actual_psize;
local_irq_save(flags);
DBG_LOW(" invalidate(vpn=%016lx, hash: %lx)\n", vpn, slot);
- want_v = hpte_encode_avpn(vpn, psize, ssize);
+ want_v = hpte_encode_avpn(vpn, bpsize, ssize);
native_lock_hpte(hptep);
hpte_v = hptep->v;
- actual_psize = hpte_actual_psize(hptep, psize);
- if (actual_psize < 0) {
- native_unlock_hpte(hptep);
- local_irq_restore(flags);
- return;
- }
- /* Even if we miss, we need to invalidate the TLB */
- if (!HPTE_V_COMPARE(hpte_v, want_v))
+ /*
+ * We need to invalidate the TLB always because hpte_remove doesn't do
+ * a tlb invalidate. If a hash bucket gets full, we "evict" a more/less
+ * random entry from it. When we do that we don't invalidate the TLB
+ * (hpte_remove) because we assume the old translation is still
technically
+ * "valid".
+ */
+ if (!HPTE_V_COMPARE(hpte_v, want_v) || !(hpte_v & HPTE_V_VALID))
native_unlock_hpte(hptep);
else
/* Invalidate the hpte. NOTE: this also unlocks it */
hptep->v = 0;
/* Invalidate the TLB */
- tlbie(vpn, psize, actual_psize, ssize, local);
+ tlbie(vpn, bpsize, apsize, ssize, local);
local_irq_restore(flags);
}
+static inline int __hpte_actual_psize(unsigned int lp, int psize)
+{
+ int i, shift;
+ unsigned int mask;
+
+ /* start from 1 ignoring MMU_PAGE_4K */
+ for (i = 1; i < MMU_PAGE_COUNT; i++) {
+
+ /* invalid penc */
+ if (mmu_psize_defs[psize].penc[i] == -1)
+ continue;
+ /*
+ * encoding bits per actual page size
+ * PTE LP actual page size
+ * rrrr rrrz >=8KB
+ * rrrr rrzz >=16KB
+ * rrrr rzzz >=32KB
+ * rrrr zzzz >=64KB
+ * .......
+ */
+ shift = mmu_psize_defs[i].shift - LP_SHIFT;
+ if (shift > LP_BITS)
+ shift = LP_BITS;
+ mask = (1 << shift) - 1;
+ if ((lp & mask) == mmu_psize_defs[psize].penc[i])
+ return i;
+ }
+ return -1;
+}
+
static void hpte_decode(struct hash_pte *hpte, unsigned long slot,
int *psize, int *apsize, int *ssize, unsigned long *vpn)
{
diff --git a/arch/powerpc/mm/hash_utils_64.c b/arch/powerpc/mm/hash_utils_64.c
index e303a6d..2f47080 100644
--- a/arch/powerpc/mm/hash_utils_64.c
+++ b/arch/powerpc/mm/hash_utils_64.c
@@ -1232,7 +1232,11 @@ void flush_hash_page(unsigned long vpn, real_pte_t pte,
int psize, int ssize,
slot = (hash & htab_hash_mask) * HPTES_PER_GROUP;
slot += hidx & _PTEIDX_GROUP_IX;
DBG_LOW(" sub %ld: hash=%lx, hidx=%lx\n", index, slot, hidx);
- ppc_md.hpte_invalidate(slot, vpn, psize, ssize, local);
+ /*
+ * We use same base page size and actual psize, because we don't
+ * use these functions for hugepage
+ */
+ ppc_md.hpte_invalidate(slot, vpn, psize, psize, ssize, local);
} pte_iterate_hashed_end();
#ifdef CONFIG_PPC_TRANSACTIONAL_MEM
@@ -1365,7 +1369,8 @@ static void kernel_unmap_linear_page(unsigned long vaddr,
unsigned long lmi)
hash = ~hash;
slot = (hash & htab_hash_mask) * HPTES_PER_GROUP;
slot += hidx & _PTEIDX_GROUP_IX;
- ppc_md.hpte_invalidate(slot, vpn, mmu_linear_psize, mmu_kernel_ssize,
0);
+ ppc_md.hpte_invalidate(slot, vpn, mmu_linear_psize, mmu_linear_psize,
+ mmu_kernel_ssize, 0);
}
void kernel_map_pages(struct page *page, int numpages, int enable)
diff --git a/arch/powerpc/mm/hugetlbpage-hash64.c
b/arch/powerpc/mm/hugetlbpage-hash64.c
index 0f1d94a..0b7fb67 100644
--- a/arch/powerpc/mm/hugetlbpage-hash64.c
+++ b/arch/powerpc/mm/hugetlbpage-hash64.c
@@ -81,7 +81,7 @@ int __hash_page_huge(unsigned long ea, unsigned long access,
unsigned long vsid,
slot += (old_pte & _PAGE_F_GIX) >> 12;
if (ppc_md.hpte_updatepp(slot, rflags, vpn, mmu_psize,
- ssize, local) == -1)
+ mmu_psize, ssize, local) == -1)
old_pte &= ~_PAGE_HPTEFLAGS;
}
diff --git a/arch/powerpc/platforms/cell/beat_htab.c
b/arch/powerpc/platforms/cell/beat_htab.c
index 246e1d8..c34ee4e 100644
--- a/arch/powerpc/platforms/cell/beat_htab.c
+++ b/arch/powerpc/platforms/cell/beat_htab.c
@@ -185,7 +185,8 @@ static void beat_lpar_hptab_clear(void)
static long beat_lpar_hpte_updatepp(unsigned long slot,
unsigned long newpp,
unsigned long vpn,
- int psize, int ssize, int local)
+ int psize, int apsize,
+ int ssize, int local)
{
unsigned long lpar_rc;
u64 dummy0, dummy1;
@@ -274,7 +275,8 @@ static void beat_lpar_hpte_updateboltedpp(unsigned long
newpp,
}
static void beat_lpar_hpte_invalidate(unsigned long slot, unsigned long vpn,
- int psize, int ssize, int local)
+ int psize, int apsize,
+ int ssize, int local)
{
unsigned long want_v;
unsigned long lpar_rc;
@@ -364,9 +366,10 @@ static long beat_lpar_hpte_insert_v3(unsigned long
hpte_group,
* already zero. For now I am paranoid.
*/
static long beat_lpar_hpte_updatepp_v3(unsigned long slot,
- unsigned long newpp,
- unsigned long vpn,
- int psize, int ssize, int local)
+ unsigned long newpp,
+ unsigned long vpn,
+ int psize, int apsize,
+ int ssize, int local)
{
unsigned long lpar_rc;
unsigned long want_v;
@@ -394,7 +397,8 @@ static long beat_lpar_hpte_updatepp_v3(unsigned long slot,
}
static void beat_lpar_hpte_invalidate_v3(unsigned long slot, unsigned long vpn,
- int psize, int ssize, int local)
+ int psize, int apsize,
+ int ssize, int local)
{
unsigned long want_v;
unsigned long lpar_rc;
diff --git a/arch/powerpc/platforms/ps3/htab.c
b/arch/powerpc/platforms/ps3/htab.c
index 177a2f7..3e270e3 100644
--- a/arch/powerpc/platforms/ps3/htab.c
+++ b/arch/powerpc/platforms/ps3/htab.c
@@ -109,7 +109,8 @@ static long ps3_hpte_remove(unsigned long hpte_group)
}
static long ps3_hpte_updatepp(unsigned long slot, unsigned long newpp,
- unsigned long vpn, int psize, int ssize, int local)
+ unsigned long vpn, int psize, int apsize,
+ int ssize, int local)
{
int result;
u64 hpte_v, want_v, hpte_rs;
@@ -162,7 +163,7 @@ static void ps3_hpte_updateboltedpp(unsigned long newpp,
unsigned long ea,
}
static void ps3_hpte_invalidate(unsigned long slot, unsigned long vpn,
- int psize, int ssize, int local)
+ int psize, int apsize, int ssize, int local)
{
unsigned long flags;
int result;
diff --git a/arch/powerpc/platforms/pseries/lpar.c
b/arch/powerpc/platforms/pseries/lpar.c
index 6d62072..ca45c8f 100644
--- a/arch/powerpc/platforms/pseries/lpar.c
+++ b/arch/powerpc/platforms/pseries/lpar.c
@@ -240,7 +240,8 @@ static void pSeries_lpar_hptab_clear(void)
static long pSeries_lpar_hpte_updatepp(unsigned long slot,
unsigned long newpp,
unsigned long vpn,
- int psize, int ssize, int local)
+ int psize, int apsize,
+ int ssize, int local)
{
unsigned long lpar_rc;
unsigned long flags = (newpp & 7) | H_AVPN;
@@ -328,7 +329,8 @@ static void pSeries_lpar_hpte_updateboltedpp(unsigned long
newpp,
}
static void pSeries_lpar_hpte_invalidate(unsigned long slot, unsigned long vpn,
- int psize, int ssize, int local)
+ int psize, int apsize,
+ int ssize, int local)
{
unsigned long want_v;
unsigned long lpar_rc;
@@ -356,8 +358,10 @@ static void pSeries_lpar_hpte_removebolted(unsigned long
ea,
slot = pSeries_lpar_hpte_find(vpn, psize, ssize);
BUG_ON(slot == -1);
-
- pSeries_lpar_hpte_invalidate(slot, vpn, psize, ssize, 0);
+ /*
+ * lpar doesn't use the passed actual page size
+ */
+ pSeries_lpar_hpte_invalidate(slot, vpn, psize, 0, ssize, 0);
}
/* Flag bits for H_BULK_REMOVE */
@@ -400,8 +404,11 @@ static void pSeries_lpar_flush_hash_range(unsigned long
number, int local)
slot = (hash & htab_hash_mask) * HPTES_PER_GROUP;
slot += hidx & _PTEIDX_GROUP_IX;
if (!firmware_has_feature(FW_FEATURE_BULK_REMOVE)) {
+ /*
+ * lpar doesn't use the passed actual page size
+ */
pSeries_lpar_hpte_invalidate(slot, vpn, psize,
- ssize, local);
+ 0, ssize, local);
} else {
param[pix] = HBR_REQUEST | HBR_AVPN | slot;
param[pix+1] = hpte_encode_avpn(vpn, psize,
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