02390f66bd
The patch 99baac21e4 ("mm: fix MADV_[FREE|DONTNEED] TLB flush miss
problem") added a force flush mode to the mmu_gather flush, which
unconditionally flushes the entire address range being invalidated
(even if actual ptes only covered a smaller range), to solve a problem
with concurrent threads invalidating the same PTEs causing them to
miss TLBs that need flushing.
This does not work with powerpc that invalidates mmu_gather batches
according to page size. Have powerpc flush all possible page sizes in
the range if it encounters this concurrency condition.
Patch 4647706ebe ("mm: always flush VMA ranges affected by
zap_page_range") does add a TLB flush for all page sizes on powerpc for
the zap_page_range case, but that is to be removed and replaced with
the mmu_gather flush to avoid redundant flushing. It is also thought to
not cover other obscure race conditions:
https://lkml.kernel.org/r/BD3A0EBE-ECF4-41D4-87FA-C755EA9AB6BD@gmail.com
Hash does not have a problem because it invalidates TLBs inside the
page table locks.
Reported-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
See Documentation/00-INDEX for a list of what is contained in each file.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.