fs/dax: Deposit pagetable even when installing zero page (11cf9d86) · Commits · 戴 / test

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: ("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>

fs/dax.c

+15 −0

Original line number	Diff line number	Diff line
		@@ -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
		@@ -1407,7 +1408,9 @@ 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;
		@@ -1422,12 +1425,22 @@ 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);
		@@ -1436,6 +1449,8 @@ 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;
		}

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