On Tue, Apr 2, 2019 at 4:51 AM Aneesh Kumar K.V <aneesh.ku...@linux.ibm.com> wrote: > > With some architectures like ppc64, set_pmd_at() cannot cope with > a situation where there is already some (different) valid entry present. > > Use pmdp_set_access_flags() instead to modify the pfn which is built to > deal with modifying existing PMD entries. > > This is similar to > commit cae85cb8add3 ("mm/memory.c: fix modifying of page protection by > insert_pfn()") > > We also do similar update w.r.t insert_pfn_pud eventhough ppc64 don't support > pud pfn entries now. > > Without this patch we also see the below message in kernel log > "BUG: non-zero pgtables_bytes on freeing mm:" > > CC: sta...@vger.kernel.org > Reported-by: Chandan Rajendra <chan...@linux.ibm.com> > Signed-off-by: Aneesh Kumar K.V <aneesh.ku...@linux.ibm.com> > --- > Changes from v1: > * Fix the pgtable leak > > mm/huge_memory.c | 36 ++++++++++++++++++++++++++++++++++++ > 1 file changed, 36 insertions(+)
This patch is triggering the following bug in v4.19.35. kernel BUG at arch/x86/mm/pgtable.c:515! invalid opcode: 0000 [#1] SMP NOPTI CPU: 51 PID: 43713 Comm: java Tainted: G OE 4.19.35 #1 RIP: 0010:pmdp_set_access_flags+0x48/0x50 [..] Call Trace: vmf_insert_pfn_pmd+0x198/0x350 dax_iomap_fault+0xe82/0x1190 ext4_dax_huge_fault+0x103/0x1f0 ? __switch_to_asm+0x40/0x70 __handle_mm_fault+0x3f6/0x1370 ? __switch_to_asm+0x34/0x70 ? __switch_to_asm+0x40/0x70 handle_mm_fault+0xda/0x200 __do_page_fault+0x249/0x4f0 do_page_fault+0x32/0x110 ? page_fault+0x8/0x30 page_fault+0x1e/0x30 I asked the reporter to try a kernel with commit c6f3c5ee40c1 "mm/huge_memory.c: fix modifying of page protection by insert_pfn_pmd()" reverted and the failing test passed. I think unaligned addresses have always been passed to vmf_insert_pfn_pmd(), but nothing cared until this patch. I *think* the only change needed is the following, thoughts? diff --git a/fs/dax.c b/fs/dax.c index ca0671d55aa6..82aee9a87efa 100644 --- a/fs/dax.c +++ b/fs/dax.c @@ -1560,7 +1560,7 @@ static vm_fault_t dax_iomap_pmd_fault(struct vm_fault *vmf, pfn_t *pfnp, } trace_dax_pmd_insert_mapping(inode, vmf, PMD_SIZE, pfn, entry); - result = vmf_insert_pfn_pmd(vma, vmf->address, vmf->pmd, pfn, + result = vmf_insert_pfn_pmd(vma, pmd_addr, vmf->pmd, pfn, write); break; case IOMAP_UNWRITTEN: I'll ask the reporter to try this fix as well. _______________________________________________ Linux-nvdimm mailing list Linux-nvdimm@lists.01.org https://lists.01.org/mailman/listinfo/linux-nvdimm