Re: [PATCH 1/2] fs/dax: deposit pagetable even when installing zero page
On 2/28/19 2:51 PM, Jan Kara wrote: On Thu 28-02-19 14:05:21, Aneesh Kumar K.V wrote: Architectures like ppc64 use the deposited page table to store hardware page table slot information. Make sure we deposit a page table when using zero page at the pmd level for hash. Without this we hit Unable to handle kernel paging request for data at address 0x Faulting instruction address: 0xc0082a74 Oops: Kernel access of bad area, sig: 11 [#1] NIP [c0082a74] __hash_page_thp+0x224/0x5b0 LR [c00829a4] __hash_page_thp+0x154/0x5b0 Call Trace: hash_page_mm+0x43c/0x740 do_hash_page+0x2c/0x3c copy_from_iter_flushcache+0xa4/0x4a0 pmem_copy_from_iter+0x2c/0x50 [nd_pmem] dax_copy_from_iter+0x40/0x70 dax_iomap_actor+0x134/0x360 iomap_apply+0xfc/0x1b0 dax_iomap_rw+0xac/0x130 ext4_file_write_iter+0x254/0x460 [ext4] __vfs_write+0x120/0x1e0 vfs_write+0xd8/0x220 SyS_write+0x6c/0x110 system_call+0x3c/0x130 Signed-off-by: Aneesh Kumar K.V Thanks for the patch. It looks good to me. You can add: Reviewed-by: Jan Kara --- TODO: * Add fixes tag Probably this is a problem since initial PPC PMEM support, isn't it? Considering ppc64 is the only broken architecture here, I guess I will use the commit that enabled PPC PMEM support here. -aneesh
Re: [PATCH 1/2] fs/dax: deposit pagetable even when installing zero page
On Thu 28-02-19 14:05:21, Aneesh Kumar K.V wrote:
> Architectures like ppc64 use the deposited page table to store hardware
> page table slot information. Make sure we deposit a page table when
> using zero page at the pmd level for hash.
>
> Without this we hit
>
> Unable to handle kernel paging request for data at address 0x
> Faulting instruction address: 0xc0082a74
> Oops: Kernel access of bad area, sig: 11 [#1]
>
>
> NIP [c0082a74] __hash_page_thp+0x224/0x5b0
> LR [c00829a4] __hash_page_thp+0x154/0x5b0
> Call Trace:
> hash_page_mm+0x43c/0x740
> do_hash_page+0x2c/0x3c
> copy_from_iter_flushcache+0xa4/0x4a0
> pmem_copy_from_iter+0x2c/0x50 [nd_pmem]
> dax_copy_from_iter+0x40/0x70
> dax_iomap_actor+0x134/0x360
> iomap_apply+0xfc/0x1b0
> dax_iomap_rw+0xac/0x130
> ext4_file_write_iter+0x254/0x460 [ext4]
> __vfs_write+0x120/0x1e0
> vfs_write+0xd8/0x220
> SyS_write+0x6c/0x110
> system_call+0x3c/0x130
>
> Signed-off-by: Aneesh Kumar K.V
Thanks for the patch. It looks good to me. You can add:
Reviewed-by: Jan Kara
> ---
> TODO:
> * Add fixes tag
Probably this is a problem since initial PPC PMEM support, isn't it?
Honza
>
> fs/dax.c | 15 +++
> 1 file changed, 15 insertions(+)
>
> diff --git a/fs/dax.c b/fs/dax.c
> index 6959837cc465..01bfb2ac34f9 100644
> --- a/fs/dax.c
> +++ b/fs/dax.c
> @@ -33,6 +33,7 @@
> #include
> #include
> #include
> +#include
> #include "internal.h"
>
> #define CREATE_TRACE_POINTS
> @@ -1410,7 +1411,9 @@ static vm_fault_t dax_pmd_load_hole(struct xa_state
> *xas, struct vm_fault *vmf,
> {
> struct address_space *mapping = vmf->vma->vm_file->f_mapping;
> unsigned long pmd_addr = vmf->address & PMD_MASK;
> + struct vm_area_struct *vma = vmf->vma;
> struct inode *inode = mapping->host;
> + pgtable_t pgtable = NULL;
> struct page *zero_page;
> spinlock_t *ptl;
> pmd_t pmd_entry;
> @@ -1425,12 +1428,22 @@ static vm_fault_t dax_pmd_load_hole(struct xa_state
> *xas, struct vm_fault *vmf,
> *entry = dax_insert_entry(xas, mapping, vmf, *entry, pfn,
> DAX_PMD | DAX_ZERO_PAGE, false);
>
> + if (arch_needs_pgtable_deposit()) {
> + pgtable = pte_alloc_one(vma->vm_mm);
> + if (!pgtable)
> + return VM_FAULT_OOM;
> + }
> +
> ptl = pmd_lock(vmf->vma->vm_mm, vmf->pmd);
> if (!pmd_none(*(vmf->pmd))) {
> spin_unlock(ptl);
> goto fallback;
> }
>
> + if (pgtable) {
> + pgtable_trans_huge_deposit(vma->vm_mm, vmf->pmd, pgtable);
> + mm_inc_nr_ptes(vma->vm_mm);
> + }
> pmd_entry = mk_pmd(zero_page, vmf->vma->vm_page_prot);
> pmd_entry = pmd_mkhuge(pmd_entry);
> set_pmd_at(vmf->vma->vm_mm, pmd_addr, vmf->pmd, pmd_entry);
> @@ -1439,6 +1452,8 @@ static vm_fault_t dax_pmd_load_hole(struct xa_state
> *xas, struct vm_fault *vmf,
> return VM_FAULT_NOPAGE;
>
> fallback:
> + if (pgtable)
> + pte_free(vma->vm_mm, pgtable);
> trace_dax_pmd_load_hole_fallback(inode, vmf, zero_page, *entry);
> return VM_FAULT_FALLBACK;
> }
> --
> 2.20.1
>
--
Jan Kara
SUSE Labs, CR
[PATCH 1/2] fs/dax: deposit pagetable even when installing zero page
Architectures like ppc64 use the deposited page table to store hardware
page table slot information. Make sure we deposit a page table when
using zero page at the pmd level for hash.
Without this we hit
Unable to handle kernel paging request for data at address 0x
Faulting instruction address: 0xc0082a74
Oops: Kernel access of bad area, sig: 11 [#1]
NIP [c0082a74] __hash_page_thp+0x224/0x5b0
LR [c00829a4] __hash_page_thp+0x154/0x5b0
Call Trace:
hash_page_mm+0x43c/0x740
do_hash_page+0x2c/0x3c
copy_from_iter_flushcache+0xa4/0x4a0
pmem_copy_from_iter+0x2c/0x50 [nd_pmem]
dax_copy_from_iter+0x40/0x70
dax_iomap_actor+0x134/0x360
iomap_apply+0xfc/0x1b0
dax_iomap_rw+0xac/0x130
ext4_file_write_iter+0x254/0x460 [ext4]
__vfs_write+0x120/0x1e0
vfs_write+0xd8/0x220
SyS_write+0x6c/0x110
system_call+0x3c/0x130
Signed-off-by: Aneesh Kumar K.V
---
TODO:
* Add fixes tag
fs/dax.c | 15 +++
1 file changed, 15 insertions(+)
diff --git a/fs/dax.c b/fs/dax.c
index 6959837cc465..01bfb2ac34f9 100644
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -33,6 +33,7 @@
#include
#include
#include
+#include
#include "internal.h"
#define CREATE_TRACE_POINTS
@@ -1410,7 +1411,9 @@ static vm_fault_t dax_pmd_load_hole(struct xa_state *xas,
struct vm_fault *vmf,
{
struct address_space *mapping = vmf->vma->vm_file->f_mapping;
unsigned long pmd_addr = vmf->address & PMD_MASK;
+ struct vm_area_struct *vma = vmf->vma;
struct inode *inode = mapping->host;
+ pgtable_t pgtable = NULL;
struct page *zero_page;
spinlock_t *ptl;
pmd_t pmd_entry;
@@ -1425,12 +1428,22 @@ static vm_fault_t dax_pmd_load_hole(struct xa_state
*xas, struct vm_fault *vmf,
*entry = dax_insert_entry(xas, mapping, vmf, *entry, pfn,
DAX_PMD | DAX_ZERO_PAGE, false);
+ if (arch_needs_pgtable_deposit()) {
+ pgtable = pte_alloc_one(vma->vm_mm);
+ if (!pgtable)
+ return VM_FAULT_OOM;
+ }
+
ptl = pmd_lock(vmf->vma->vm_mm, vmf->pmd);
if (!pmd_none(*(vmf->pmd))) {
spin_unlock(ptl);
goto fallback;
}
+ if (pgtable) {
+ pgtable_trans_huge_deposit(vma->vm_mm, vmf->pmd, pgtable);
+ mm_inc_nr_ptes(vma->vm_mm);
+ }
pmd_entry = mk_pmd(zero_page, vmf->vma->vm_page_prot);
pmd_entry = pmd_mkhuge(pmd_entry);
set_pmd_at(vmf->vma->vm_mm, pmd_addr, vmf->pmd, pmd_entry);
@@ -1439,6 +1452,8 @@ static vm_fault_t dax_pmd_load_hole(struct xa_state *xas,
struct vm_fault *vmf,
return VM_FAULT_NOPAGE;
fallback:
+ if (pgtable)
+ pte_free(vma->vm_mm, pgtable);
trace_dax_pmd_load_hole_fallback(inode, vmf, zero_page, *entry);
return VM_FAULT_FALLBACK;
}
--
2.20.1
