Messages in this thread | | | Subject | Re: [PATCH v12 05/31] mm: prepare for FAULT_FLAG_SPECULATIVE | From | Laurent Dufour <> | Date | Tue, 23 Apr 2019 17:45:51 +0200 |
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Le 19/04/2019 à 00:04, Jerome Glisse a écrit : > On Tue, Apr 16, 2019 at 03:44:56PM +0200, Laurent Dufour wrote: >> From: Peter Zijlstra <peterz@infradead.org> >> >> When speculating faults (without holding mmap_sem) we need to validate >> that the vma against which we loaded pages is still valid when we're >> ready to install the new PTE. >> >> Therefore, replace the pte_offset_map_lock() calls that (re)take the >> PTL with pte_map_lock() which can fail in case we find the VMA changed >> since we started the fault. >> >> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> >> >> [Port to 4.12 kernel] >> [Remove the comment about the fault_env structure which has been >> implemented as the vm_fault structure in the kernel] >> [move pte_map_lock()'s definition upper in the file] >> [move the define of FAULT_FLAG_SPECULATIVE later in the series] >> [review error path in do_swap_page(), do_anonymous_page() and >> wp_page_copy()] >> Signed-off-by: Laurent Dufour <ldufour@linux.ibm.com> > > Reviewed-by: Jérôme Glisse <jglisse@redhat.com> > >> --- >> mm/memory.c | 87 +++++++++++++++++++++++++++++++++++------------------ >> 1 file changed, 58 insertions(+), 29 deletions(-) >> >> diff --git a/mm/memory.c b/mm/memory.c >> index c6ddadd9d2b7..fc3698d13cb5 100644 >> --- a/mm/memory.c >> +++ b/mm/memory.c >> @@ -2073,6 +2073,13 @@ int apply_to_page_range(struct mm_struct *mm, unsigned long addr, >> } >> EXPORT_SYMBOL_GPL(apply_to_page_range); >> >> +static inline bool pte_map_lock(struct vm_fault *vmf) > > I am not fan of the name maybe pte_offset_map_lock_if_valid() ? But > that just a taste thing. So feel free to ignore this comment.
I agree with you that adding _if_valid or something equivalent to highlight the conditional of this function would be a good idea.
I'll think further about that name but yours looks good ;)
>> +{ >> + vmf->pte = pte_offset_map_lock(vmf->vma->vm_mm, vmf->pmd, >> + vmf->address, &vmf->ptl); >> + return true; >> +} >> + >> /* >> * handle_pte_fault chooses page fault handler according to an entry which was >> * read non-atomically. Before making any commitment, on those architectures >
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