# git rev-parse -q --verify 8b11ec1b5ffb54f71cb5a5e5c8c4d36e5d113085^{commit}
8b11ec1b5ffb54f71cb5a5e5c8c4d36e5d113085
already have revision, skipping fetch
# git checkout -q -f -B kisskb 8b11ec1b5ffb54f71cb5a5e5c8c4d36e5d113085
# git clean -qxdf
# < git log -1
# commit 8b11ec1b5ffb54f71cb5a5e5c8c4d36e5d113085
# Author: Linus Torvalds <torvalds@linux-foundation.org>
# Date:   Wed Aug 1 13:43:38 2018 -0700
# 
#     mm: do not initialize TLB stack vma's with vma_init()
#     
#     Commit 2c4541e24c55 ("mm: use vma_init() to initialize VMAs on stack and
#     data segments") tried to initialize various left-over ad-hoc vma's
#     "properly", but actually made things worse for the temporary vma's used
#     for TLB flushing.
#     
#     vma_init() doesn't actually initialize all of the vma, just a few
#     fields, so doing something like
#     
#        -       struct vm_area_struct vma = { .vm_mm = tlb->mm, };
#        +       struct vm_area_struct vma;
#        +
#        +       vma_init(&vma, tlb->mm);
#     
#     was actually very bad: instead of having a nicely initialized vma with
#     every field but "vm_mm" zeroed, you'd have an entirely uninitialized vma
#     with only a couple of fields initialized.  And they weren't even fields
#     that the code in question mostly cared about.
#     
#     The flush_tlb_range() function takes a "struct vma" rather than a
#     "struct mm_struct", because a few architectures actually care about what
#     kind of range it is - being able to only do an ITLB flush if it's a
#     range that doesn't have data accesses enabled, for example.  And all the
#     normal users already have the vma for doing the range invalidation.
#     
#     But a few people want to call flush_tlb_range() with a range they just
#     made up, so they also end up using a made-up vma.  x86 just has a
#     special "flush_tlb_mm_range()" function for this, but other
#     architectures (arm and ia64) do the "use fake vma" thing instead, and
#     thus got caught up in the vma_init() changes.
#     
#     At the same time, the TLB flushing code really doesn't care about most
#     other fields in the vma, so vma_init() is just unnecessary and
#     pointless.
#     
#     This fixes things by having an explicit "this is just an initializer for
#     the TLB flush" initializer macro, which is used by the arm/arm64/ia64
#     people who mis-use this interface with just a dummy vma.
#     
#     Fixes: 2c4541e24c55 ("mm: use vma_init() to initialize VMAs on stack and data segments")
#     Cc: Dmitry Vyukov <dvyukov@google.com>
#     Cc: Oleg Nesterov <oleg@redhat.com>
#     Cc: Andrea Arcangeli <aarcange@redhat.com>
#     Cc: Kirill Shutemov <kirill.shutemov@linux.intel.com>
#     Cc: Andrew Morton <akpm@linux-foundation.org>
#     Cc: John Stultz <john.stultz@linaro.org>
#     Cc: Hugh Dickins <hughd@google.com>
#     Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
# < /opt/cross/kisskb/or1k-linux-5.4.0-20170218/or1k-linux/bin/or1k-linux-gcc --version
# < git log --format=%s --max-count=1 8b11ec1b5ffb54f71cb5a5e5c8c4d36e5d113085
# < make -s -j 10 ARCH=openrisc O=/kisskb/build/linus_or1ksim_defconfig_or32 CROSS_COMPILE=/opt/cross/kisskb/or1k-linux-5.4.0-20170218/or1k-linux/bin/or1k-linux-  or1ksim_defconfig
# make -s -j 10 ARCH=openrisc O=/kisskb/build/linus_or1ksim_defconfig_or32 CROSS_COMPILE=/opt/cross/kisskb/or1k-linux-5.4.0-20170218/or1k-linux/bin/or1k-linux-  
<stdin>:1335:2: warning: #warning syscall rseq not implemented [-Wcpp]
Completed OK
# rm -rf /kisskb/build/linus_or1ksim_defconfig_or32
# Build took: 0:00:29.865141