| Message ID | 20190228083522.8189-1-aneesh.kumar@linux.ibm.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [1/2] fs/dax: deposit pagetable even when installing zero page | expand |
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 0x00000000 > Faulting instruction address: 0xc000000000082a74 > Oops: Kernel access of bad area, sig: 11 [#1] > .... > > NIP [c000000000082a74] __hash_page_thp+0x224/0x5b0 > LR [c0000000000829a4] __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 <aneesh.kumar@linux.ibm.com> Thanks for the patch. It looks good to me. You can add: Reviewed-by: Jan Kara <jack@suse.cz> > --- > 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 <linux/sizes.h> > #include <linux/mmu_notifier.h> > #include <linux/iomap.h> > +#include <asm/pgalloc.h> > #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 >
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 0x00000000 >> Faulting instruction address: 0xc000000000082a74 >> Oops: Kernel access of bad area, sig: 11 [#1] >> .... >> >> NIP [c000000000082a74] __hash_page_thp+0x224/0x5b0 >> LR [c0000000000829a4] __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 <aneesh.kumar@linux.ibm.com> > > Thanks for the patch. It looks good to me. You can add: > > Reviewed-by: Jan Kara <jack@suse.cz> > >> --- >> 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
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 <linux/sizes.h> #include <linux/mmu_notifier.h> #include <linux/iomap.h> +#include <asm/pgalloc.h> #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; }
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 0x00000000 Faulting instruction address: 0xc000000000082a74 Oops: Kernel access of bad area, sig: 11 [#1] .... NIP [c000000000082a74] __hash_page_thp+0x224/0x5b0 LR [c0000000000829a4] __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 <aneesh.kumar@linux.ibm.com> --- TODO: * Add fixes tag fs/dax.c | 15 +++++++++++++++ 1 file changed, 15 insertions(+)