| Message ID | 1455236836-24579-1-git-send-email-toshi.kani@hpe.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Thu, Feb 11, 2016 at 05:27:16PM -0700, Toshi Kani wrote: > The following oops was observed when a read syscall was made to > a pmem device after a huge amount (>512GB) of vmalloc ranges was > allocated by ioremap() on a x86_64 system. > > BUG: unable to handle kernel paging request at ffff880840000ff8 > IP: [<ffffffff810664ae>] vmalloc_fault+0x1be/0x300 > PGD c7f03a067 PUD 0 > Oops: 0000 [#1] SM > : > Call Trace: > [<ffffffff81067335>] __do_page_fault+0x285/0x3e0 > [<ffffffff810674bf>] do_page_fault+0x2f/0x80 > [<ffffffff810d6d85>] ? put_prev_entity+0x35/0x7a0 > [<ffffffff817a6888>] page_fault+0x28/0x30 > [<ffffffff813bb976>] ? memcpy_erms+0x6/0x10 > [<ffffffff817a0845>] ? schedule+0x35/0x80 > [<ffffffffa006350a>] ? pmem_rw_bytes+0x6a/0x190 [nd_pmem] > [<ffffffff817a3713>] ? schedule_timeout+0x183/0x240 > [<ffffffffa028d2b3>] btt_log_read+0x63/0x140 [nd_btt] > : > [<ffffffff811201d0>] ? __symbol_put+0x60/0x60 > [<ffffffff8122dc60>] ? kernel_read+0x50/0x80 > [<ffffffff81124489>] SyS_finit_module+0xb9/0xf0 > [<ffffffff817a4632>] entry_SYSCALL_64_fastpath+0x1a/0xa4 Please remove those virtual addresses and offsets here as they're meaningless and leave only the callstack. > Since 4.1, ioremap() supports large page (pud/pmd) mappings in > x86_64 and PAE. vmalloc_fault() however assumes that the vmalloc > range is limited to pte mappings. > > vmalloc faults do not normally happen in ioremap'd ranges since > ioremap() sets up the kernel page tables, which are shared by > user processes. pgd_ctor() sets the kernel's pgd entries to > user's during fork(). When allocation of the vmalloc ranges > crosses a 512GB boundary, ioremap() allocates a new pud table > and updates the kernel pgd entry to point it. If user process's > pgd entry does not have this update yet, a read/write syscall > to the range will cause a vmalloc fault, which hits the Oops > above as it does not handle a large page properly. > > Following changes are made to vmalloc_fault(). > > 64-bit: > - No change for the pgd sync operation as it handles large > pages already. > - Add pud_huge() and pmd_huge() to the validation code to > handle large pages. > - Change pud_page_vaddr() to pud_pfn() since an ioremap range > is not directly mapped (while the if-statement still works > with a bogus addr). > - Change pmd_page() to pmd_pfn() since an ioremap range is not > backed by struct page (while the if-statement still works > with a bogus addr). > > 32-bit: > - No change for the sync operation since the index3 pgd entry > covers the entire vmalloc range, which is always valid. > (A separate change to sync pgd entry is necessary if this > memory layout is changed regardless of the page size.) > - Add pmd_huge() to the validation code to handle large pages. > This is for completeness since vmalloc_fault() won't happen > in ioremap'd ranges as its pgd entry is always valid. > > Reported-by: Henning Schild <henning.schild@siemens.com> > Signed-off-by: Toshi Kani <toshi.kani@hpe.com> > Cc: Thomas Gleixner <tglx@linutronix.de> > Cc: Ingo Molnar <mingo@redhat.com> > Cc: "H. Peter Anvin" <hpa@zytor.com> > Cc: Borislav Petkov <bp@alien8.de> > --- > When this patch is accepted, please copy to stable up to 4.1. You can do that yourself when submitting by adding this to the CC-list above. Cc: <stable@vger.kernel.org> # 4.1.. Rest looks ok to me.
On Sat, 2016-02-13 at 12:54 +0100, Borislav Petkov wrote: > On Thu, Feb 11, 2016 at 05:27:16PM -0700, Toshi Kani wrote: > > The following oops was observed when a read syscall was made to > > a pmem device after a huge amount (>512GB) of vmalloc ranges was > > allocated by ioremap() on a x86_64 system. > > > > BUG: unable to handle kernel paging request at ffff880840000ff8 > > IP: [<ffffffff810664ae>] vmalloc_fault+0x1be/0x300 > > PGD c7f03a067 PUD 0 > > Oops: 0000 [#1] SM > > : > > Call Trace: > > [<ffffffff81067335>] __do_page_fault+0x285/0x3e0 > > [<ffffffff810674bf>] do_page_fault+0x2f/0x80 > > [<ffffffff810d6d85>] ? put_prev_entity+0x35/0x7a0 > > [<ffffffff817a6888>] page_fault+0x28/0x30 > > [<ffffffff813bb976>] ? memcpy_erms+0x6/0x10 > > [<ffffffff817a0845>] ? schedule+0x35/0x80 > > [<ffffffffa006350a>] ? pmem_rw_bytes+0x6a/0x190 [nd_pmem] > > [<ffffffff817a3713>] ? schedule_timeout+0x183/0x240 > > [<ffffffffa028d2b3>] btt_log_read+0x63/0x140 [nd_btt] > > : > > [<ffffffff811201d0>] ? __symbol_put+0x60/0x60 > > [<ffffffff8122dc60>] ? kernel_read+0x50/0x80 > > [<ffffffff81124489>] SyS_finit_module+0xb9/0xf0 > > [<ffffffff817a4632>] entry_SYSCALL_64_fastpath+0x1a/0xa4 > > Please remove those virtual addresses and offsets here as they're > meaningless and leave only the callstack. Will do. : > > --- > > When this patch is accepted, please copy to stable up to 4.1. > > You can do that yourself when submitting by adding this to the CC-list > above. > > Cc: <stable@vger.kernel.org> # 4.1.. I see. I will add it to the next version. > Rest looks ok to me. Great! Thanks, -Toshi
diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c index eef44d9..e830c71 100644 --- a/arch/x86/mm/fault.c +++ b/arch/x86/mm/fault.c @@ -287,6 +287,9 @@ static noinline int vmalloc_fault(unsigned long address) if (!pmd_k) return -1; + if (pmd_huge(*pmd_k)) + return 0; + pte_k = pte_offset_kernel(pmd_k, address); if (!pte_present(*pte_k)) return -1; @@ -360,8 +363,6 @@ void vmalloc_sync_all(void) * 64-bit: * * Handle a fault on the vmalloc area - * - * This assumes no large pages in there. */ static noinline int vmalloc_fault(unsigned long address) { @@ -403,17 +404,23 @@ static noinline int vmalloc_fault(unsigned long address) if (pud_none(*pud_ref)) return -1; - if (pud_none(*pud) || pud_page_vaddr(*pud) != pud_page_vaddr(*pud_ref)) + if (pud_none(*pud) || pud_pfn(*pud) != pud_pfn(*pud_ref)) BUG(); + if (pud_huge(*pud)) + return 0; + pmd = pmd_offset(pud, address); pmd_ref = pmd_offset(pud_ref, address); if (pmd_none(*pmd_ref)) return -1; - if (pmd_none(*pmd) || pmd_page(*pmd) != pmd_page(*pmd_ref)) + if (pmd_none(*pmd) || pmd_pfn(*pmd) != pmd_pfn(*pmd_ref)) BUG(); + if (pmd_huge(*pmd)) + return 0; + pte_ref = pte_offset_kernel(pmd_ref, address); if (!pte_present(*pte_ref)) return -1;
The following oops was observed when a read syscall was made to a pmem device after a huge amount (>512GB) of vmalloc ranges was allocated by ioremap() on a x86_64 system. BUG: unable to handle kernel paging request at ffff880840000ff8 IP: [<ffffffff810664ae>] vmalloc_fault+0x1be/0x300 PGD c7f03a067 PUD 0 Oops: 0000 [#1] SM : Call Trace: [<ffffffff81067335>] __do_page_fault+0x285/0x3e0 [<ffffffff810674bf>] do_page_fault+0x2f/0x80 [<ffffffff810d6d85>] ? put_prev_entity+0x35/0x7a0 [<ffffffff817a6888>] page_fault+0x28/0x30 [<ffffffff813bb976>] ? memcpy_erms+0x6/0x10 [<ffffffff817a0845>] ? schedule+0x35/0x80 [<ffffffffa006350a>] ? pmem_rw_bytes+0x6a/0x190 [nd_pmem] [<ffffffff817a3713>] ? schedule_timeout+0x183/0x240 [<ffffffffa028d2b3>] btt_log_read+0x63/0x140 [nd_btt] : [<ffffffff811201d0>] ? __symbol_put+0x60/0x60 [<ffffffff8122dc60>] ? kernel_read+0x50/0x80 [<ffffffff81124489>] SyS_finit_module+0xb9/0xf0 [<ffffffff817a4632>] entry_SYSCALL_64_fastpath+0x1a/0xa4 Since 4.1, ioremap() supports large page (pud/pmd) mappings in x86_64 and PAE. vmalloc_fault() however assumes that the vmalloc range is limited to pte mappings. vmalloc faults do not normally happen in ioremap'd ranges since ioremap() sets up the kernel page tables, which are shared by user processes. pgd_ctor() sets the kernel's pgd entries to user's during fork(). When allocation of the vmalloc ranges crosses a 512GB boundary, ioremap() allocates a new pud table and updates the kernel pgd entry to point it. If user process's pgd entry does not have this update yet, a read/write syscall to the range will cause a vmalloc fault, which hits the Oops above as it does not handle a large page properly. Following changes are made to vmalloc_fault(). 64-bit: - No change for the pgd sync operation as it handles large pages already. - Add pud_huge() and pmd_huge() to the validation code to handle large pages. - Change pud_page_vaddr() to pud_pfn() since an ioremap range is not directly mapped (while the if-statement still works with a bogus addr). - Change pmd_page() to pmd_pfn() since an ioremap range is not backed by struct page (while the if-statement still works with a bogus addr). 32-bit: - No change for the sync operation since the index3 pgd entry covers the entire vmalloc range, which is always valid. (A separate change to sync pgd entry is necessary if this memory layout is changed regardless of the page size.) - Add pmd_huge() to the validation code to handle large pages. This is for completeness since vmalloc_fault() won't happen in ioremap'd ranges as its pgd entry is always valid. Reported-by: Henning Schild <henning.schild@siemens.com> Signed-off-by: Toshi Kani <toshi.kani@hpe.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@redhat.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Borislav Petkov <bp@alien8.de> --- When this patch is accepted, please copy to stable up to 4.1. v2: Add more descriptions about the issue in the change log. --- arch/x86/mm/fault.c | 15 +++++++++++---- 1 file changed, 11 insertions(+), 4 deletions(-)