Re: FAILED: patch "[PATCH] mm/huge_memory.c: thp: fix conflict of above-47bit hint" failed to apply to 4.19-stable tree

[Sasha Levin <sashal@kernel.org>]

On Sun, Jan 19, 2020 at 04:15:02PM +0100, gregkh@linuxfoundation.org wrote:
>
>The patch below does not apply to the 4.19-stable tree.
>If someone wants it applied there, or to any other stable or longterm
>tree, then please email the backport, including the original git commit
>id to <stable@vger.kernel.org>.
>
>thanks,
>
>greg k-h
>
>------------------ original commit in Linus's tree ------------------
>
>From 97d3d0f9a1cf132c63c0b8b8bd497b8a56283dd9 Mon Sep 17 00:00:00 2001
>From: "Kirill A. Shutemov" <kirill@shutemov.name>
>Date: Mon, 13 Jan 2020 16:29:10 -0800
>Subject: [PATCH] mm/huge_memory.c: thp: fix conflict of above-47bit hint
> address and PMD alignment
>
>Patch series "Fix two above-47bit hint address vs.  THP bugs".
>
>The two get_unmapped_area() implementations have to be fixed to provide
>THP-friendly mappings if above-47bit hint address is specified.
>
>This patch (of 2):
>
>Filesystems use thp_get_unmapped_area() to provide THP-friendly
>mappings.  For DAX in particular.
>
>Normally, the kernel doesn't create userspace mappings above 47-bit,
>even if the machine allows this (such as with 5-level paging on x86-64).
>Not all user space is ready to handle wide addresses.  It's known that
>at least some JIT compilers use higher bits in pointers to encode their
>information.
>
>Userspace can ask for allocation from full address space by specifying
>hint address (with or without MAP_FIXED) above 47-bits.  If the
>application doesn't need a particular address, but wants to allocate
>from whole address space it can specify -1 as a hint address.
>
>Unfortunately, this trick breaks thp_get_unmapped_area(): the function
>would not try to allocate PMD-aligned area if *any* hint address
>specified.
>
>Modify the routine to handle it correctly:
>
> - Try to allocate the space at the specified hint address with length
>   padding required for PMD alignment.
> - If failed, retry without length padding (but with the same hint
>   address);
> - If the returned address matches the hint address return it.
> - Otherwise, align the address as required for THP and return.
>
>The user specified hint address is passed down to get_unmapped_area() so
>above-47bit hint address will be taken into account without breaking
>alignment requirements.
>
>Link: http://lkml.kernel.org/r/20191220142548.7118-2-kirill.shutemov@linux.intel.com
>Fixes: b569bab78d8d ("x86/mm: Prepare to expose larger address space to userspace")
>Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
>Reported-by: Thomas Willhalm <thomas.willhalm@intel.com>
>Tested-by: Dan Williams <dan.j.williams@intel.com>
>Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.vnet.ibm.com>
>Cc: "Bruggeman, Otto G" <otto.g.bruggeman@intel.com>
>Cc: <stable@vger.kernel.org>
>Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
>Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Conflict due to missing b3b07077b01e ("mm/huge_memory.c: make
__thp_get_unmapped_area static"), I've just queued both for 4.19 and
4.14.

-- 
Thanks,
Sasha