wireguard-linux/arch/arc/mm, branch jd/unified-crypt-queue

mm: allow VM_FAULT_RETRY for multiple times

2020-04-02T16:35:30Z

The idea comes from a discussion between Linus and Andrea [1]. Before this patch we only allow a page fault to retry once. We achieved this by clearing the FAULT_FLAG_ALLOW_RETRY flag when doing handle_mm_fault() the second time. This was majorly used to avoid unexpected starvation of the system by looping over forever to handle the page fault on a single page. However that should hardly happen, and after all for each code path to return a VM_FAULT_RETRY we'll first wait for a condition (during which time we should possibly yield the cpu) to happen before VM_FAULT_RETRY is really returned. This patch removes the restriction by keeping the FAULT_FLAG_ALLOW_RETRY flag when we receive VM_FAULT_RETRY. It means that the page fault handler now can retry the page fault for multiple times if necessary without the need to generate another page fault event. Meanwhile we still keep the FAULT_FLAG_TRIED flag so page fault handler can still identify whether a page fault is the first attempt or not. Then we'll have these combinations of fault flags (only considering ALLOW_RETRY flag and TRIED flag): - ALLOW_RETRY and !TRIED: this means the page fault allows to retry, and this is the first try - ALLOW_RETRY and TRIED: this means the page fault allows to retry, and this is not the first try - !ALLOW_RETRY and !TRIED: this means the page fault does not allow to retry at all - !ALLOW_RETRY and TRIED: this is forbidden and should never be used In existing code we have multiple places that has taken special care of the first condition above by checking against (fault_flags & FAULT_FLAG_ALLOW_RETRY). This patch introduces a simple helper to detect the first retry of a page fault by checking against both (fault_flags & FAULT_FLAG_ALLOW_RETRY) and !(fault_flag & FAULT_FLAG_TRIED) because now even the 2nd try will have the ALLOW_RETRY set, then use that helper in all existing special paths. One example is in __lock_page_or_retry(), now we'll drop the mmap_sem only in the first attempt of page fault and we'll keep it in follow up retries, so old locking behavior will be retained. This will be a nice enhancement for current code [2] at the same time a supporting material for the future userfaultfd-writeprotect work, since in that work there will always be an explicit userfault writeprotect retry for protected pages, and if that cannot resolve the page fault (e.g., when userfaultfd-writeprotect is used in conjunction with swapped pages) then we'll possibly need a 3rd retry of the page fault. It might also benefit other potential users who will have similar requirement like userfault write-protection. GUP code is not touched yet and will be covered in follow up patch. Please read the thread below for more information. [1] https://lore.kernel.org/lkml/20171102193644.GB22686@redhat.com/ [2] https://lore.kernel.org/lkml/20181230154648.GB9832@redhat.com/ Suggested-by: Linus Torvalds Suggested-by: Andrea Arcangeli Signed-off-by: Peter Xu Signed-off-by: Andrew Morton Tested-by: Brian Geffon Cc: Bobby Powers Cc: David Hildenbrand Cc: Denis Plotnikov Cc: "Dr . David Alan Gilbert" Cc: Hugh Dickins Cc: Jerome Glisse Cc: Johannes Weiner Cc: "Kirill A . Shutemov" Cc: Martin Cracauer Cc: Marty McFadden Cc: Matthew Wilcox Cc: Maya Gokhale Cc: Mel Gorman Cc: Mike Kravetz Cc: Mike Rapoport Cc: Pavel Emelyanov Link: http://lkml.kernel.org/r/20200220160246.9790-1-peterx@redhat.com Signed-off-by: Linus Torvalds

mm: introduce FAULT_FLAG_DEFAULT

2020-04-02T16:35:29Z

Although there're tons of arch-specific page fault handlers, most of them are still sharing the same initial value of the page fault flags. Say, merely all of the page fault handlers would allow the fault to be retried, and they also allow the fault to respond to SIGKILL. Let's define a default value for the fault flags to replace those initial page fault flags that were copied over. With this, it'll be far easier to introduce new fault flag that can be used by all the architectures instead of touching all the archs. Signed-off-by: Peter Xu Signed-off-by: Andrew Morton Tested-by: Brian Geffon Reviewed-by: David Hildenbrand Cc: Andrea Arcangeli Cc: Bobby Powers Cc: Denis Plotnikov Cc: "Dr . David Alan Gilbert" Cc: Hugh Dickins Cc: Jerome Glisse Cc: Johannes Weiner Cc: "Kirill A . Shutemov" Cc: Martin Cracauer Cc: Marty McFadden Cc: Matthew Wilcox Cc: Maya Gokhale Cc: Mel Gorman Cc: Mike Kravetz Cc: Mike Rapoport Cc: Pavel Emelyanov Link: http://lkml.kernel.org/r/20200220160238.9694-1-peterx@redhat.com Signed-off-by: Linus Torvalds

arc/mm: use helper fault_signal_pending()

2020-04-02T16:35:29Z

Let ARC to use the new helper fault_signal_pending() by moving the signal check out of the retry logic as standalone. This should also helps to simplify the code a bit. Signed-off-by: Peter Xu Signed-off-by: Andrew Morton Tested-by: Brian Geffon Cc: Andrea Arcangeli Cc: Bobby Powers Cc: David Hildenbrand Cc: Denis Plotnikov Cc: "Dr . David Alan Gilbert" Cc: Hugh Dickins Cc: Jerome Glisse Cc: Johannes Weiner Cc: "Kirill A . Shutemov" Cc: Martin Cracauer Cc: Marty McFadden Cc: Matthew Wilcox Cc: Maya Gokhale Cc: Mel Gorman Cc: Mike Kravetz Cc: Mike Rapoport Cc: Pavel Emelyanov Link: http://lkml.kernel.org/r/20200220155843.9172-1-peterx@redhat.com Signed-off-by: Linus Torvalds

Merge tag 'arc-5.5-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/vgupta/arc

2019-12-05T03:06:18Z

Pull ARC updates from Vineet Gupta - Jump Label support for ARC - kmemleak enabled - arc mm backend TLB Miss / flush optimizations - nSIM platform switching to dwuart (vs. arcuart) and ensuing defconfig updates and cleanups - axs platform pll / video-mode updates * tag 'arc-5.5-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/vgupta/arc: ARC: add kmemleak support ARC: [plat-axs10x]: remove hardcoded video mode from bootargs ARC: [plat-axs10x]: use pgu pll instead of fixed clock ARC: ARCv2: jump label: implement jump label patching ARC: mm: tlb flush optim: elide redundant uTLB invalidates for MMUv3 ARC: mm: tlb flush optim: elide repeated uTLB invalidate in loop ARC: mm: tlb flush optim: Make TLBWriteNI fallback to TLBWrite if not available ARC: mm: TLB Miss optim: avoid re-reading ECR ARCv2: mm: TLB Miss optim: Use double world load/stores LDD/STD ARCv2: mm: TLB Miss optim: SMP builds can cache pgd pointer in mmu scratch reg ARC: nSIM_700: remove unused network options ARC: nSIM_700: switch to DW UART usage ARC: merge HAPS-HS with nSIM-HS configs ARC: HAPS: cleanup defconfigs from unused ETH drivers ARC: HAPS: add HIGHMEM memory zone to DTS ARC: HAPS: use same UART configuration everywhere ARC: HAPS: cleanup defconfigs from unused IO-related options ARC: regenerate nSIM and HAPS defconfigs

ARC: mm: remove __ARCH_USE_5LEVEL_HACK

2019-12-01T14:29:19Z

Patch series "elide extraneous generated code for folded p4d/pud/pmd", v3. This series came out of seemingly benign excursion into understanding/removing __ARCH_USE_5LEVEL_HACK from ARC port showing some extraneous code being generated despite folded p4d/pud/pmd | bloat-o-meter2 vmlinux-[AB]* | add/remove: 0/0 grow/shrink: 3/0 up/down: 130/0 (130) | function old new delta | free_pgd_range 548 660 +112 | p4d_clear_bad 2 20 +18 The patches here address that | bloat-o-meter2 vmlinux-[BF]* | add/remove: 0/2 grow/shrink: 0/1 up/down: 0/-386 (-386) | function old new delta | pud_clear_bad 20 - -20 | p4d_clear_bad 20 - -20 | free_pgd_range 660 314 -346 The code savings are not a whole lot, but still worthwhile IMHO. This patch (of 5): With paging code made 5-level compliant, this is no longer needed. ARC has software page walker with 2 lookup levels (pgd -> pte) This was expected to be non functional change but ended with slight code bloat due to needless inclusions of p*d_free_tlb() macros which will be addressed in further patches. | bloat-o-meter2 vmlinux-[AB]* | add/remove: 0/0 grow/shrink: 2/0 up/down: 128/0 (128) | function old new delta | free_pgd_range 546 656 +110 | p4d_clear_bad 2 20 +18 | Total: Before=4137148, After=4137276, chg 0.000000% Link: http://lkml.kernel.org/r/20191016162400.14796-2-vgupta@synopsys.com Signed-off-by: Vineet Gupta Acked-by: Kirill A. Shutemov Cc: "Aneesh Kumar K . V" Cc: Arnd Bergmann Cc: Nick Piggin Cc: Peter Zijlstra Cc: Will Deacon Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

dma-mapping: drop the dev argument to arch_sync_dma_for_*

2019-11-20T19:31:38Z

These are pure cache maintainance routines, so drop the unused struct device argument. Signed-off-by: Christoph Hellwig Suggested-by: Daniel Vetter

ARC: mm: tlb flush optim: elide redundant uTLB invalidates for MMUv3

2019-10-28T19:12:32Z

For MMUv3 (and prior) the flush_tlb_{range,mm,page} API use the MMU TLBWrite cmd which already nukes the entire uTLB, so NO need for additional IVUTLB cmd from utlb_invalidate() - hence this patch local_flush_tlb_all() is special since it uses a weaker TLBWriteNI cmd (prec commit) to shoot down JTLB, hence we retain the explicit uTLB flush Signed-off-by: Vineet Gupta

ARC: mm: tlb flush optim: elide repeated uTLB invalidate in loop

2019-10-28T19:12:32Z

The unconditional full TLB flush (on say ASID rollover) iterates over each entry and uses TLBWrite to zero it out. TLBWrite by design also invalidates the uTLBs thus we end up invalidating it as many times as numbe rof entries (512 or 1k) Optimize this by using a weaker TLBWriteNI cmd in loop, which doesn't tinker with uTLBs and an explicit one time IVUTLB, outside the loop to invalidate them all once. And given the optimiztion, the IVUTLB is now needed on MMUv4 too where the uTLBs and JTLBs are otherwise coherent given the TLBInsertEntry / TLBDeleteEntry commands Signed-off-by: Vineet Gupta

ARC: mm: tlb flush optim: Make TLBWriteNI fallback to TLBWrite if not available

2019-10-28T19:12:32Z

TLBWriteNI was introduced in MMUv2 (to not invalidate uTLBs in Fast Path TLB Refill Handler). To avoid #ifdef'ery make it fallback to TLBWrite availabel on all MMUs. This will also help with next change Signed-off-by: Vineet Gupta

ARC: mm: TLB Miss optim: avoid re-reading ECR

2019-10-28T19:12:32Z

For setting PTE Dirty bit, reuse the prior test for ST miss. No need to reload ECR and test for ST cause code as the prev condition code is still valid (uncloberred) Signed-off-by: Vineet Gupta