From: Aneesh Kumar K.V aneesh.kumar@linux.ibm.com
commit 11cf9d863dcb583345723b0ed72173348761e9c0 upstream.
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
Fixes: b5beae5e224f ("powerpc/pseries: Add driver for PAPR SCM regions") Cc: stable@vger.kernel.org Reviewed-by: Jan Kara jack@suse.cz Signed-off-by: Aneesh Kumar K.V aneesh.kumar@linux.ibm.com Signed-off-by: Dan Williams dan.j.williams@intel.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- fs/dax.c | 15 +++++++++++++++ 1 file changed, 15 insertions(+)
--- 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 @@ -1409,7 +1410,9 @@ static vm_fault_t dax_pmd_load_hole(stru { 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; @@ -1424,12 +1427,22 @@ static vm_fault_t dax_pmd_load_hole(stru *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); @@ -1438,6 +1451,8 @@ static vm_fault_t dax_pmd_load_hole(stru 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; }