main/linux-rpi: update rpi patch

3 files changed, 2 insertions, 918 deletions

diff --git a/main/linux-rpi/APKBUILD b/main/linux-rpi/APKBUILD
index eba8e6a764..8e53f8ded3 100644
--- a/main/linux-rpi/APKBUILD
+++ b/main/linux-rpi/APKBUILD
@@ -18,11 +18,9 @@ install=
 # rpi-cirrus-4.4.y  https://github.com/HiassofT/rpi-linux/tree/cirrus-4.4.y
 source="https://kernel.org/pub/linux/kernel/v4.x/linux-$_kernver.tar.xz
 	https://kernel.org/pub/linux/kernel/v4.x/patch-$pkgver.xz
-	https://dev.alpinelinux.org/~clandmeter/patches/linux-4.9.y-rpi-201704120.patch
+	https://dev.alpinelinux.org/~clandmeter/patches/linux-v${pkgver}-rpi.patch.gz
 	gpio-mcp23s08-pullups.patch
 	issue-4973.patch
-	mm-larger-stack-guard-gap-between-vmas.patch
-	mm-guard-against-under-sized-gap-in-unmapped_area-_topdown.patch
 
 	config-rpi.armhf
 	config-rpi2.armhf
@@ -197,11 +195,9 @@ _dev() {
 
 sha512sums="bf67ff812cc3cb7e5059e82cc5db0d9a7c5637f7ed9a42e4730c715bf7047c81ed3a571225f92a33ef0b6d65f35595bc32d773356646df2627da55e9bc7f1f1a  linux-4.9.tar.xz
 ab9c26493069f87a9d8c6c97db1a84f03a1b1221f47facc68e65d79ef75d9c7bd93c1f39eee334e4f45381b2c84ff3acb8870478c61c4d8a648984db55be5ad3  patch-4.9.40.xz
-1586b4c549285bb3015e99288c08cbbad719c7b40156fdb4ab7849a07363d2cc29045ae0037f0873994d3c36812be2ed2ee530c6fbfce5a86e6ebf83480d0db2  linux-4.9.y-rpi-201704120.patch
+2cbeb943eb296ded385593b7e7e2309d78ea040581bdb75e131544ee5d4b8a867e80a76cfbc170271b85ef0c6925526d20e1cb6945031a5eb40dd18c225b0fbe  linux-v4.9.40-rpi.patch.gz
 36724ba56cb8fdf3a3d347cffb67ae1cc3d7b1052d526b6b5134ebf6baae9f9724b586c97833453dc7697ab24699426f0749af78b6a80be36967a80033a0cf40  gpio-mcp23s08-pullups.patch
 501c91bf2538a18102da59bbccc3097f9c3c90079acc0e946ff075074160c09b8a66934e5ce5470e170f0e4f93d114709a95230367426d0bb7ea02c4bdf4cc9b  issue-4973.patch
-69f03e4a0020c0b9f196a02f326503c03f5fb192d191ccbc21a30a422b115e6873dfd925df594da1d8b0c3477ead98c8e0757fd1e3128fd703339b352fda0299  mm-larger-stack-guard-gap-between-vmas.patch
-567b70b5f634d7d8f79f5f70f7fdf0aee46dab6b865d6a62ee5a5a0dded69eb47008d86f4d639b7261beedce6a7df44a1d3e51e0fe5902b4c51b6b83e3b146a3  mm-guard-against-under-sized-gap-in-unmapped_area-_topdown.patch
 54dc88144fc7d502499878f588e5f0f3312991ce49b9245a2790cb1d1224b4f71a4751b7cd29b29e2b2b17d64b65d8d49198f6fbd545a9322faf25041e4bdc06  config-rpi.armhf
 626369f71ef271f6722e8e297cbdaf9cc4d57c9bfda264eac473f006f54a5697f45a757e0930d98523ed8c63a880a89a8258a55ab99bd720a84acd4ee46d5010  config-rpi2.armhf
 a8e7f434c325c9dd7a9109efecad408e42a50ecd1391cb0c7d1d7de79609caee007486c8a6538231c74bdc5d7b84cbca053958e1b239bc0507e6d3598ace383a  markdt"
diff --git a/main/linux-rpi/mm-guard-against-under-sized-gap-in-unmapped_area-_topdown.patch b/main/linux-rpi/mm-guard-against-under-sized-gap-in-unmapped_area-_topdown.patch
deleted file mode 100644
index 5472fb5f19..0000000000
--- a/main/linux-rpi/mm-guard-against-under-sized-gap-in-unmapped_area-_topdown.patch
+++ /dev/null
@@ -1,27 +0,0 @@
-Author: Hugh Dickins <hughd@google.com>
-Date: Mon, 19 Jun 2017 21:40:56 -0700
-Description: mm: Guard against under-sized gap in unmapped_area{,_topdown}()
-Origin: https://www.mail-archive.com/linux-kernel@vger.kernel.org/msg1426125.html
-
---- a/mm/mmap.c
-+++ b/mm/mmap.c
-@@ -1817,7 +1817,8 @@ unsigned long unmapped_area(struct vm_un
- 		/* Check if current node has a suitable gap */
- 		if (gap_start > high_limit)
- 			return -ENOMEM;
--		if (gap_end >= low_limit && gap_end - gap_start >= length)
-+		if (gap_end >= low_limit &&
-+		    gap_end > gap_start && gap_end - gap_start >= length)
- 			goto found;
- 
- 		/* Visit right subtree if it looks promising */
-@@ -1920,7 +1921,8 @@ unsigned long unmapped_area_topdown(stru
- 		gap_end = vm_start_gap(vma);
- 		if (gap_end < low_limit)
- 			return -ENOMEM;
--		if (gap_start <= high_limit && gap_end - gap_start >= length)
-+		if (gap_start <= high_limit &&
-+		    gap_end > gap_start && gap_end - gap_start >= length)
- 			goto found;
- 
- 		/* Visit left subtree if it looks promising */
diff --git a/main/linux-rpi/mm-larger-stack-guard-gap-between-vmas.patch b/main/linux-rpi/mm-larger-stack-guard-gap-between-vmas.patch
deleted file mode 100644
index af4e9c6980..0000000000
--- a/main/linux-rpi/mm-larger-stack-guard-gap-between-vmas.patch
+++ /dev/null
@@ -1,885 +0,0 @@
-From: Hugh Dickins <hughd@google.com>
-Date: Mon, 19 Jun 2017 04:03:24 -0700
-Subject: mm: larger stack guard gap, between vmas
-
-commit 1be7107fbe18eed3e319a6c3e83c78254b693acb upstream.
-
-Stack guard page is a useful feature to reduce a risk of stack smashing
-into a different mapping. We have been using a single page gap which
-is sufficient to prevent having stack adjacent to a different mapping.
-But this seems to be insufficient in the light of the stack usage in
-userspace. E.g. glibc uses as large as 64kB alloca() in many commonly
-used functions. Others use constructs liks gid_t buffer[NGROUPS_MAX]
-which is 256kB or stack strings with MAX_ARG_STRLEN.
-
-This will become especially dangerous for suid binaries and the default
-no limit for the stack size limit because those applications can be
-tricked to consume a large portion of the stack and a single glibc call
-could jump over the guard page. These attacks are not theoretical,
-unfortunatelly.
-
-Make those attacks less probable by increasing the stack guard gap
-to 1MB (on systems with 4k pages; but make it depend on the page size
-because systems with larger base pages might cap stack allocations in
-the PAGE_SIZE units) which should cover larger alloca() and VLA stack
-allocations. It is obviously not a full fix because the problem is
-somehow inherent, but it should reduce attack space a lot.
-
-One could argue that the gap size should be configurable from userspace,
-but that can be done later when somebody finds that the new 1MB is wrong
-for some special case applications.  For now, add a kernel command line
-option (stack_guard_gap) to specify the stack gap size (in page units).
-
-Implementation wise, first delete all the old code for stack guard page:
-because although we could get away with accounting one extra page in a
-stack vma, accounting a larger gap can break userspace - case in point,
-a program run with "ulimit -S -v 20000" failed when the 1MB gap was
-counted for RLIMIT_AS; similar problems could come with RLIMIT_MLOCK
-and strict non-overcommit mode.
-
-Instead of keeping gap inside the stack vma, maintain the stack guard
-gap as a gap between vmas: using vm_start_gap() in place of vm_start
-(or vm_end_gap() in place of vm_end if VM_GROWSUP) in just those few
-places which need to respect the gap - mainly arch_get_unmapped_area(),
-and and the vma tree's subtree_gap support for that.
-
-Original-patch-by: Oleg Nesterov <oleg@redhat.com>
-Original-patch-by: Michal Hocko <mhocko@suse.com>
-Signed-off-by: Hugh Dickins <hughd@google.com>
-Acked-by: Michal Hocko <mhocko@suse.com>
-Tested-by: Helge Deller <deller@gmx.de> # parisc
-Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-[wt: backport to 4.11: adjust context]
-[wt: backport to 4.9: adjust context ; kernel doc was not in admin-guide]
-Signed-off-by: Willy Tarreau <w@1wt.eu>
-Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
----
- Documentation/kernel-parameters.txt |    7 +
- arch/arc/mm/mmap.c                  |    2 
- arch/arm/mm/mmap.c                  |    4 
- arch/frv/mm/elf-fdpic.c             |    2 
- arch/mips/mm/mmap.c                 |    2 
- arch/parisc/kernel/sys_parisc.c     |   15 ++-
- arch/powerpc/mm/hugetlbpage-radix.c |    2 
- arch/powerpc/mm/mmap.c              |    4 
- arch/powerpc/mm/slice.c             |    2 
- arch/s390/mm/mmap.c                 |    4 
- arch/sh/mm/mmap.c                   |    4 
- arch/sparc/kernel/sys_sparc_64.c    |    4 
- arch/sparc/mm/hugetlbpage.c         |    2 
- arch/tile/mm/hugetlbpage.c          |    2 
- arch/x86/kernel/sys_x86_64.c        |    4 
- arch/x86/mm/hugetlbpage.c           |    2 
- arch/xtensa/kernel/syscall.c        |    2 
- fs/hugetlbfs/inode.c                |    2 
- fs/proc/task_mmu.c                  |    4 
- include/linux/mm.h                  |   53 ++++++------
- mm/gup.c                            |    5 -
- mm/memory.c                         |   38 ---------
- mm/mmap.c                           |  149 +++++++++++++++++++++---------------
- 23 files changed, 152 insertions(+), 163 deletions(-)
-
---- a/Documentation/kernel-parameters.txt
-+++ b/Documentation/kernel-parameters.txt
-@@ -3932,6 +3932,13 @@ bytes respectively. Such letter suffixes
- 	spia_pedr=
- 	spia_peddr=
- 
-+	stack_guard_gap=	[MM]
-+			override the default stack gap protection. The value
-+			is in page units and it defines how many pages prior
-+			to (for stacks growing down) resp. after (for stacks
-+			growing up) the main stack are reserved for no other
-+			mapping. Default value is 256 pages.
-+
- 	stacktrace	[FTRACE]
- 			Enabled the stack tracer on boot up.
- 
---- a/arch/arc/mm/mmap.c
-+++ b/arch/arc/mm/mmap.c
-@@ -64,7 +64,7 @@ arch_get_unmapped_area(struct file *filp
- 
- 		vma = find_vma(mm, addr);
- 		if (TASK_SIZE - len >= addr &&
--		    (!vma || addr + len <= vma->vm_start))
-+		    (!vma || addr + len <= vm_start_gap(vma)))
- 			return addr;
- 	}
- 
---- a/arch/arm/mm/mmap.c
-+++ b/arch/arm/mm/mmap.c
-@@ -89,7 +89,7 @@ arch_get_unmapped_area(struct file *filp
- 
- 		vma = find_vma(mm, addr);
- 		if (TASK_SIZE - len >= addr &&
--		    (!vma || addr + len <= vma->vm_start))
-+		    (!vma || addr + len <= vm_start_gap(vma)))
- 			return addr;
- 	}
- 
-@@ -140,7 +140,7 @@ arch_get_unmapped_area_topdown(struct fi
- 			addr = PAGE_ALIGN(addr);
- 		vma = find_vma(mm, addr);
- 		if (TASK_SIZE - len >= addr &&
--				(!vma || addr + len <= vma->vm_start))
-+				(!vma || addr + len <= vm_start_gap(vma)))
- 			return addr;
- 	}
- 
---- a/arch/frv/mm/elf-fdpic.c
-+++ b/arch/frv/mm/elf-fdpic.c
-@@ -74,7 +74,7 @@ unsigned long arch_get_unmapped_area(str
- 		addr = PAGE_ALIGN(addr);
- 		vma = find_vma(current->mm, addr);
- 		if (TASK_SIZE - len >= addr &&
--		    (!vma || addr + len <= vma->vm_start))
-+		    (!vma || addr + len <= vm_start_gap(vma)))
- 			goto success;
- 	}
- 
---- a/arch/mips/mm/mmap.c
-+++ b/arch/mips/mm/mmap.c
-@@ -92,7 +92,7 @@ static unsigned long arch_get_unmapped_a
- 
- 		vma = find_vma(mm, addr);
- 		if (TASK_SIZE - len >= addr &&
--		    (!vma || addr + len <= vma->vm_start))
-+		    (!vma || addr + len <= vm_start_gap(vma)))
- 			return addr;
- 	}
- 
---- a/arch/parisc/kernel/sys_parisc.c
-+++ b/arch/parisc/kernel/sys_parisc.c
-@@ -88,7 +88,7 @@ unsigned long arch_get_unmapped_area(str
- 		unsigned long len, unsigned long pgoff, unsigned long flags)
- {
- 	struct mm_struct *mm = current->mm;
--	struct vm_area_struct *vma;
-+	struct vm_area_struct *vma, *prev;
- 	unsigned long task_size = TASK_SIZE;
- 	int do_color_align, last_mmap;
- 	struct vm_unmapped_area_info info;
-@@ -115,9 +115,10 @@ unsigned long arch_get_unmapped_area(str
- 		else
- 			addr = PAGE_ALIGN(addr);
- 
--		vma = find_vma(mm, addr);
-+		vma = find_vma_prev(mm, addr, &prev);
- 		if (task_size - len >= addr &&
--		    (!vma || addr + len <= vma->vm_start))
-+		    (!vma || addr + len <= vm_start_gap(vma)) &&
-+		    (!prev || addr >= vm_end_gap(prev)))
- 			goto found_addr;
- 	}
- 
-@@ -141,7 +142,7 @@ arch_get_unmapped_area_topdown(struct fi
- 			  const unsigned long len, const unsigned long pgoff,
- 			  const unsigned long flags)
- {
--	struct vm_area_struct *vma;
-+	struct vm_area_struct *vma, *prev;
- 	struct mm_struct *mm = current->mm;
- 	unsigned long addr = addr0;
- 	int do_color_align, last_mmap;
-@@ -175,9 +176,11 @@ arch_get_unmapped_area_topdown(struct fi
- 			addr = COLOR_ALIGN(addr, last_mmap, pgoff);
- 		else
- 			addr = PAGE_ALIGN(addr);
--		vma = find_vma(mm, addr);
-+
-+		vma = find_vma_prev(mm, addr, &prev);
- 		if (TASK_SIZE - len >= addr &&
--		    (!vma || addr + len <= vma->vm_start))
-+		    (!vma || addr + len <= vm_start_gap(vma)) &&
-+		    (!prev || addr >= vm_end_gap(prev)))
- 			goto found_addr;
- 	}
- 
---- a/arch/powerpc/mm/hugetlbpage-radix.c
-+++ b/arch/powerpc/mm/hugetlbpage-radix.c
-@@ -65,7 +65,7 @@ radix__hugetlb_get_unmapped_area(struct
- 		addr = ALIGN(addr, huge_page_size(h));
- 		vma = find_vma(mm, addr);
- 		if (TASK_SIZE - len >= addr &&
--		    (!vma || addr + len <= vma->vm_start))
-+		    (!vma || addr + len <= vm_start_gap(vma)))
- 			return addr;
- 	}
- 	/*
---- a/arch/powerpc/mm/mmap.c
-+++ b/arch/powerpc/mm/mmap.c
-@@ -106,7 +106,7 @@ radix__arch_get_unmapped_area(struct fil
- 		addr = PAGE_ALIGN(addr);
- 		vma = find_vma(mm, addr);
- 		if (TASK_SIZE - len >= addr && addr >= mmap_min_addr &&
--		    (!vma || addr + len <= vma->vm_start))
-+		    (!vma || addr + len <= vm_start_gap(vma)))
- 			return addr;
- 	}
- 
-@@ -142,7 +142,7 @@ radix__arch_get_unmapped_area_topdown(st
- 		addr = PAGE_ALIGN(addr);
- 		vma = find_vma(mm, addr);
- 		if (TASK_SIZE - len >= addr && addr >= mmap_min_addr &&
--				(!vma || addr + len <= vma->vm_start))
-+				(!vma || addr + len <= vm_start_gap(vma)))
- 			return addr;
- 	}
- 
---- a/arch/powerpc/mm/slice.c
-+++ b/arch/powerpc/mm/slice.c
-@@ -105,7 +105,7 @@ static int slice_area_is_free(struct mm_
- 	if ((mm->task_size - len) < addr)
- 		return 0;
- 	vma = find_vma(mm, addr);
--	return (!vma || (addr + len) <= vma->vm_start);
-+	return (!vma || (addr + len) <= vm_start_gap(vma));
- }
- 
- static int slice_low_has_vma(struct mm_struct *mm, unsigned long slice)
---- a/arch/s390/mm/mmap.c
-+++ b/arch/s390/mm/mmap.c
-@@ -98,7 +98,7 @@ arch_get_unmapped_area(struct file *filp
- 		addr = PAGE_ALIGN(addr);
- 		vma = find_vma(mm, addr);
- 		if (TASK_SIZE - len >= addr && addr >= mmap_min_addr &&
--		    (!vma || addr + len <= vma->vm_start))
-+		    (!vma || addr + len <= vm_start_gap(vma)))
- 			return addr;
- 	}
- 
-@@ -136,7 +136,7 @@ arch_get_unmapped_area_topdown(struct fi
- 		addr = PAGE_ALIGN(addr);
- 		vma = find_vma(mm, addr);
- 		if (TASK_SIZE - len >= addr && addr >= mmap_min_addr &&
--				(!vma || addr + len <= vma->vm_start))
-+				(!vma || addr + len <= vm_start_gap(vma)))
- 			return addr;
- 	}
- 
---- a/arch/sh/mm/mmap.c
-+++ b/arch/sh/mm/mmap.c
-@@ -63,7 +63,7 @@ unsigned long arch_get_unmapped_area(str
- 
- 		vma = find_vma(mm, addr);
- 		if (TASK_SIZE - len >= addr &&
--		    (!vma || addr + len <= vma->vm_start))
-+		    (!vma || addr + len <= vm_start_gap(vma)))
- 			return addr;
- 	}
- 
-@@ -113,7 +113,7 @@ arch_get_unmapped_area_topdown(struct fi
- 
- 		vma = find_vma(mm, addr);
- 		if (TASK_SIZE - len >= addr &&
--		    (!vma || addr + len <= vma->vm_start))
-+		    (!vma || addr + len <= vm_start_gap(vma)))
- 			return addr;
- 	}
- 
---- a/arch/sparc/kernel/sys_sparc_64.c
-+++ b/arch/sparc/kernel/sys_sparc_64.c
-@@ -118,7 +118,7 @@ unsigned long arch_get_unmapped_area(str
- 
- 		vma = find_vma(mm, addr);
- 		if (task_size - len >= addr &&
--		    (!vma || addr + len <= vma->vm_start))
-+		    (!vma || addr + len <= vm_start_gap(vma)))
- 			return addr;
- 	}
- 
-@@ -181,7 +181,7 @@ arch_get_unmapped_area_topdown(struct fi
- 
- 		vma = find_vma(mm, addr);
- 		if (task_size - len >= addr &&
--		    (!vma || addr + len <= vma->vm_start))
-+		    (!vma || addr + len <= vm_start_gap(vma)))
- 			return addr;
- 	}
- 
---- a/arch/sparc/mm/hugetlbpage.c
-+++ b/arch/sparc/mm/hugetlbpage.c
-@@ -116,7 +116,7 @@ hugetlb_get_unmapped_area(struct file *f
- 		addr = ALIGN(addr, HPAGE_SIZE);
- 		vma = find_vma(mm, addr);
- 		if (task_size - len >= addr &&
--		    (!vma || addr + len <= vma->vm_start))
-+		    (!vma || addr + len <= vm_start_gap(vma)))
- 			return addr;
- 	}
- 	if (mm->get_unmapped_area == arch_get_unmapped_area)
---- a/arch/tile/mm/hugetlbpage.c
-+++ b/arch/tile/mm/hugetlbpage.c
-@@ -232,7 +232,7 @@ unsigned long hugetlb_get_unmapped_area(
- 		addr = ALIGN(addr, huge_page_size(h));
- 		vma = find_vma(mm, addr);
- 		if (TASK_SIZE - len >= addr &&
--		    (!vma || addr + len <= vma->vm_start))
-+		    (!vma || addr + len <= vm_start_gap(vma)))
- 			return addr;
- 	}
- 	if (current->mm->get_unmapped_area == arch_get_unmapped_area)
---- a/arch/x86/kernel/sys_x86_64.c
-+++ b/arch/x86/kernel/sys_x86_64.c
-@@ -140,7 +140,7 @@ arch_get_unmapped_area(struct file *filp
- 		addr = PAGE_ALIGN(addr);
- 		vma = find_vma(mm, addr);
- 		if (end - len >= addr &&
--		    (!vma || addr + len <= vma->vm_start))
-+		    (!vma || addr + len <= vm_start_gap(vma)))
- 			return addr;
- 	}
- 
-@@ -183,7 +183,7 @@ arch_get_unmapped_area_topdown(struct fi
- 		addr = PAGE_ALIGN(addr);
- 		vma = find_vma(mm, addr);
- 		if (TASK_SIZE - len >= addr &&
--				(!vma || addr + len <= vma->vm_start))
-+				(!vma || addr + len <= vm_start_gap(vma)))
- 			return addr;
- 	}
- 
---- a/arch/x86/mm/hugetlbpage.c
-+++ b/arch/x86/mm/hugetlbpage.c
-@@ -144,7 +144,7 @@ hugetlb_get_unmapped_area(struct file *f
- 		addr = ALIGN(addr, huge_page_size(h));
- 		vma = find_vma(mm, addr);
- 		if (TASK_SIZE - len >= addr &&
--		    (!vma || addr + len <= vma->vm_start))
-+		    (!vma || addr + len <= vm_start_gap(vma)))
- 			return addr;
- 	}
- 	if (mm->get_unmapped_area == arch_get_unmapped_area)
---- a/arch/xtensa/kernel/syscall.c
-+++ b/arch/xtensa/kernel/syscall.c
-@@ -87,7 +87,7 @@ unsigned long arch_get_unmapped_area(str
- 		/* At this point:  (!vmm || addr < vmm->vm_end). */
- 		if (TASK_SIZE - len < addr)
- 			return -ENOMEM;
--		if (!vmm || addr + len <= vmm->vm_start)
-+		if (!vmm || addr + len <= vm_start_gap(vmm))
- 			return addr;
- 		addr = vmm->vm_end;
- 		if (flags & MAP_SHARED)
---- a/fs/hugetlbfs/inode.c
-+++ b/fs/hugetlbfs/inode.c
-@@ -191,7 +191,7 @@ hugetlb_get_unmapped_area(struct file *f
- 		addr = ALIGN(addr, huge_page_size(h));
- 		vma = find_vma(mm, addr);
- 		if (TASK_SIZE - len >= addr &&
--		    (!vma || addr + len <= vma->vm_start))
-+		    (!vma || addr + len <= vm_start_gap(vma)))
- 			return addr;
- 	}
- 
---- a/fs/proc/task_mmu.c
-+++ b/fs/proc/task_mmu.c
-@@ -299,11 +299,7 @@ show_map_vma(struct seq_file *m, struct
- 
- 	/* We don't show the stack guard page in /proc/maps */
- 	start = vma->vm_start;
--	if (stack_guard_page_start(vma, start))
--		start += PAGE_SIZE;
- 	end = vma->vm_end;
--	if (stack_guard_page_end(vma, end))
--		end -= PAGE_SIZE;
- 
- 	seq_setwidth(m, 25 + sizeof(void *) * 6 - 1);
- 	seq_printf(m, "%08lx-%08lx %c%c%c%c %08llx %02x:%02x %lu ",
---- a/include/linux/mm.h
-+++ b/include/linux/mm.h
-@@ -1356,39 +1356,11 @@ int clear_page_dirty_for_io(struct page
- 
- int get_cmdline(struct task_struct *task, char *buffer, int buflen);
- 
--/* Is the vma a continuation of the stack vma above it? */
--static inline int vma_growsdown(struct vm_area_struct *vma, unsigned long addr)
--{
--	return vma && (vma->vm_end == addr) && (vma->vm_flags & VM_GROWSDOWN);
--}
--
- static inline bool vma_is_anonymous(struct vm_area_struct *vma)
- {
- 	return !vma->vm_ops;
- }
- 
--static inline int stack_guard_page_start(struct vm_area_struct *vma,
--					     unsigned long addr)
--{
--	return (vma->vm_flags & VM_GROWSDOWN) &&
--		(vma->vm_start == addr) &&
--		!vma_growsdown(vma->vm_prev, addr);
--}
--
--/* Is the vma a continuation of the stack vma below it? */
--static inline int vma_growsup(struct vm_area_struct *vma, unsigned long addr)
--{
--	return vma && (vma->vm_start == addr) && (vma->vm_flags & VM_GROWSUP);
--}
--
--static inline int stack_guard_page_end(struct vm_area_struct *vma,
--					   unsigned long addr)
--{
--	return (vma->vm_flags & VM_GROWSUP) &&
--		(vma->vm_end == addr) &&
--		!vma_growsup(vma->vm_next, addr);
--}
--
- int vma_is_stack_for_current(struct vm_area_struct *vma);
- 
- extern unsigned long move_page_tables(struct vm_area_struct *vma,
-@@ -2127,6 +2099,7 @@ void page_cache_async_readahead(struct a
- 				pgoff_t offset,
- 				unsigned long size);
- 
-+extern unsigned long stack_guard_gap;
- /* Generic expand stack which grows the stack according to GROWS{UP,DOWN} */
- extern int expand_stack(struct vm_area_struct *vma, unsigned long address);
- 
-@@ -2155,6 +2128,30 @@ static inline struct vm_area_struct * fi
- 	return vma;
- }
- 
-+static inline unsigned long vm_start_gap(struct vm_area_struct *vma)
-+{
-+	unsigned long vm_start = vma->vm_start;
-+
-+	if (vma->vm_flags & VM_GROWSDOWN) {
-+		vm_start -= stack_guard_gap;
-+		if (vm_start > vma->vm_start)
-+			vm_start = 0;
-+	}
-+	return vm_start;
-+}
-+
-+static inline unsigned long vm_end_gap(struct vm_area_struct *vma)
-+{
-+	unsigned long vm_end = vma->vm_end;
-+
-+	if (vma->vm_flags & VM_GROWSUP) {
-+		vm_end += stack_guard_gap;
-+		if (vm_end < vma->vm_end)
-+			vm_end = -PAGE_SIZE;
-+	}
-+	return vm_end;
-+}
-+
- static inline unsigned long vma_pages(struct vm_area_struct *vma)
- {
- 	return (vma->vm_end - vma->vm_start) >> PAGE_SHIFT;
---- a/mm/gup.c
-+++ b/mm/gup.c
-@@ -370,11 +370,6 @@ static int faultin_page(struct task_stru
- 	/* mlock all present pages, but do not fault in new pages */
- 	if ((*flags & (FOLL_POPULATE | FOLL_MLOCK)) == FOLL_MLOCK)
- 		return -ENOENT;
--	/* For mm_populate(), just skip the stack guard page. */
--	if ((*flags & FOLL_POPULATE) &&
--			(stack_guard_page_start(vma, address) ||
--			 stack_guard_page_end(vma, address + PAGE_SIZE)))
--		return -ENOENT;
- 	if (*flags & FOLL_WRITE)
- 		fault_flags |= FAULT_FLAG_WRITE;
- 	if (*flags & FOLL_REMOTE)
---- a/mm/memory.c
-+++ b/mm/memory.c
-@@ -2699,40 +2699,6 @@ out_release:
- }
- 
- /*
-- * This is like a special single-page "expand_{down|up}wards()",
-- * except we must first make sure that 'address{-|+}PAGE_SIZE'
-- * doesn't hit another vma.
-- */
--static inline int check_stack_guard_page(struct vm_area_struct *vma, unsigned long address)
--{
--	address &= PAGE_MASK;
--	if ((vma->vm_flags & VM_GROWSDOWN) && address == vma->vm_start) {
--		struct vm_area_struct *prev = vma->vm_prev;
--
--		/*
--		 * Is there a mapping abutting this one below?
--		 *
--		 * That's only ok if it's the same stack mapping
--		 * that has gotten split..
--		 */
--		if (prev && prev->vm_end == address)
--			return prev->vm_flags & VM_GROWSDOWN ? 0 : -ENOMEM;
--
--		return expand_downwards(vma, address - PAGE_SIZE);
--	}
--	if ((vma->vm_flags & VM_GROWSUP) && address + PAGE_SIZE == vma->vm_end) {
--		struct vm_area_struct *next = vma->vm_next;
--
--		/* As VM_GROWSDOWN but s/below/above/ */
--		if (next && next->vm_start == address + PAGE_SIZE)
--			return next->vm_flags & VM_GROWSUP ? 0 : -ENOMEM;
--
--		return expand_upwards(vma, address + PAGE_SIZE);
--	}
--	return 0;
--}
--
--/*
-  * We enter with non-exclusive mmap_sem (to exclude vma changes,
-  * but allow concurrent faults), and pte mapped but not yet locked.
-  * We return with mmap_sem still held, but pte unmapped and unlocked.
-@@ -2748,10 +2714,6 @@ static int do_anonymous_page(struct faul
- 	if (vma->vm_flags & VM_SHARED)
- 		return VM_FAULT_SIGBUS;
- 
--	/* Check if we need to add a guard page to the stack */
--	if (check_stack_guard_page(vma, fe->address) < 0)
--		return VM_FAULT_SIGSEGV;
--
- 	/*
- 	 * Use pte_alloc() instead of pte_alloc_map().  We can't run
- 	 * pte_offset_map() on pmds where a huge pmd might be created
---- a/mm/mmap.c
-+++ b/mm/mmap.c
-@@ -183,6 +183,7 @@ SYSCALL_DEFINE1(brk, unsigned long, brk)
- 	unsigned long retval;
- 	unsigned long newbrk, oldbrk;
- 	struct mm_struct *mm = current->mm;
-+	struct vm_area_struct *next;
- 	unsigned long min_brk;
- 	bool populate;
- 
-@@ -228,7 +229,8 @@ SYSCALL_DEFINE1(brk, unsigned long, brk)
- 	}
- 
- 	/* Check against existing mmap mappings. */
--	if (find_vma_intersection(mm, oldbrk, newbrk+PAGE_SIZE))
-+	next = find_vma(mm, oldbrk);
-+	if (next && newbrk + PAGE_SIZE > vm_start_gap(next))
- 		goto out;
- 
- 	/* Ok, looks good - let it rip. */
-@@ -251,10 +253,22 @@ out:
- 
- static long vma_compute_subtree_gap(struct vm_area_struct *vma)
- {
--	unsigned long max, subtree_gap;
--	max = vma->vm_start;
--	if (vma->vm_prev)
--		max -= vma->vm_prev->vm_end;
-+	unsigned long max, prev_end, subtree_gap;
-+
-+	/*
-+	 * Note: in the rare case of a VM_GROWSDOWN above a VM_GROWSUP, we
-+	 * allow two stack_guard_gaps between them here, and when choosing
-+	 * an unmapped area; whereas when expanding we only require one.
-+	 * That's a little inconsistent, but keeps the code here simpler.
-+	 */
-+	max = vm_start_gap(vma);
-+	if (vma->vm_prev) {
-+		prev_end = vm_end_gap(vma->vm_prev);
-+		if (max > prev_end)
-+			max -= prev_end;
-+		else
-+			max = 0;
-+	}
- 	if (vma->vm_rb.rb_left) {
- 		subtree_gap = rb_entry(vma->vm_rb.rb_left,
- 				struct vm_area_struct, vm_rb)->rb_subtree_gap;
-@@ -350,7 +364,7 @@ static void validate_mm(struct mm_struct
- 			anon_vma_unlock_read(anon_vma);
- 		}
- 
--		highest_address = vma->vm_end;
-+		highest_address = vm_end_gap(vma);
- 		vma = vma->vm_next;
- 		i++;
- 	}
-@@ -539,7 +553,7 @@ void __vma_link_rb(struct mm_struct *mm,
- 	if (vma->vm_next)
- 		vma_gap_update(vma->vm_next);
- 	else
--		mm->highest_vm_end = vma->vm_end;
-+		mm->highest_vm_end = vm_end_gap(vma);
- 
- 	/*
- 	 * vma->vm_prev wasn't known when we followed the rbtree to find the
-@@ -854,7 +868,7 @@ again:
- 			vma_gap_update(vma);
- 		if (end_changed) {
- 			if (!next)
--				mm->highest_vm_end = end;
-+				mm->highest_vm_end = vm_end_gap(vma);
- 			else if (!adjust_next)
- 				vma_gap_update(next);
- 		}
-@@ -939,7 +953,7 @@ again:
- 			 * mm->highest_vm_end doesn't need any update
- 			 * in remove_next == 1 case.
- 			 */
--			VM_WARN_ON(mm->highest_vm_end != end);
-+			VM_WARN_ON(mm->highest_vm_end != vm_end_gap(vma));
- 		}
- 	}
- 	if (insert && file)
-@@ -1783,7 +1797,7 @@ unsigned long unmapped_area(struct vm_un
- 
- 	while (true) {
- 		/* Visit left subtree if it looks promising */
--		gap_end = vma->vm_start;
-+		gap_end = vm_start_gap(vma);
- 		if (gap_end >= low_limit && vma->vm_rb.rb_left) {
- 			struct vm_area_struct *left =
- 				rb_entry(vma->vm_rb.rb_left,
-@@ -1794,7 +1808,7 @@ unsigned long unmapped_area(struct vm_un
- 			}
- 		}
- 
--		gap_start = vma->vm_prev ? vma->vm_prev->vm_end : 0;
-+		gap_start = vma->vm_prev ? vm_end_gap(vma->vm_prev) : 0;
- check_current:
- 		/* Check if current node has a suitable gap */
- 		if (gap_start > high_limit)
-@@ -1821,8 +1835,8 @@ check_current:
- 			vma = rb_entry(rb_parent(prev),
- 				       struct vm_area_struct, vm_rb);
- 			if (prev == vma->vm_rb.rb_left) {
--				gap_start = vma->vm_prev->vm_end;
--				gap_end = vma->vm_start;
-+				gap_start = vm_end_gap(vma->vm_prev);
-+				gap_end = vm_start_gap(vma);
- 				goto check_current;
- 			}
- 		}
-@@ -1886,7 +1900,7 @@ unsigned long unmapped_area_topdown(stru
- 
- 	while (true) {
- 		/* Visit right subtree if it looks promising */
--		gap_start = vma->vm_prev ? vma->vm_prev->vm_end : 0;
-+		gap_start = vma->vm_prev ? vm_end_gap(vma->vm_prev) : 0;
- 		if (gap_start <= high_limit && vma->vm_rb.rb_right) {
- 			struct vm_area_struct *right =
- 				rb_entry(vma->vm_rb.rb_right,
-@@ -1899,7 +1913,7 @@ unsigned long unmapped_area_topdown(stru
- 
- check_current:
- 		/* Check if current node has a suitable gap */
--		gap_end = vma->vm_start;
-+		gap_end = vm_start_gap(vma);
- 		if (gap_end < low_limit)
- 			return -ENOMEM;
- 		if (gap_start <= high_limit && gap_end - gap_start >= length)
-@@ -1925,7 +1939,7 @@ check_current:
- 				       struct vm_area_struct, vm_rb);
- 			if (prev == vma->vm_rb.rb_right) {
- 				gap_start = vma->vm_prev ?
--					vma->vm_prev->vm_end : 0;
-+					vm_end_gap(vma->vm_prev) : 0;
- 				goto check_current;
- 			}
- 		}
-@@ -1963,7 +1977,7 @@ arch_get_unmapped_area(struct file *filp
- 		unsigned long len, unsigned long pgoff, unsigned long flags)
- {
- 	struct mm_struct *mm = current->mm;
--	struct vm_area_struct *vma;
-+	struct vm_area_struct *vma, *prev;
- 	struct vm_unmapped_area_info info;
- 
- 	if (len > TASK_SIZE - mmap_min_addr)
-@@ -1974,9 +1988,10 @@ arch_get_unmapped_area(struct file *filp
- 
- 	if (addr) {
- 		addr = PAGE_ALIGN(addr);
--		vma = find_vma(mm, addr);
-+		vma = find_vma_prev(mm, addr, &prev);
- 		if (TASK_SIZE - len >= addr && addr >= mmap_min_addr &&
--		    (!vma || addr + len <= vma->vm_start))
-+		    (!vma || addr + len <= vm_start_gap(vma)) &&
-+		    (!prev || addr >= vm_end_gap(prev)))
- 			return addr;
- 	}
- 
-@@ -1999,7 +2014,7 @@ arch_get_unmapped_area_topdown(struct fi
- 			  const unsigned long len, const unsigned long pgoff,
- 			  const unsigned long flags)
- {
--	struct vm_area_struct *vma;
-+	struct vm_area_struct *vma, *prev;
- 	struct mm_struct *mm = current->mm;
- 	unsigned long addr = addr0;
- 	struct vm_unmapped_area_info info;
-@@ -2014,9 +2029,10 @@ arch_get_unmapped_area_topdown(struct fi
- 	/* requesting a specific address */
- 	if (addr) {
- 		addr = PAGE_ALIGN(addr);
--		vma = find_vma(mm, addr);
-+		vma = find_vma_prev(mm, addr, &prev);
- 		if (TASK_SIZE - len >= addr && addr >= mmap_min_addr &&
--				(!vma || addr + len <= vma->vm_start))
-+				(!vma || addr + len <= vm_start_gap(vma)) &&
-+				(!prev || addr >= vm_end_gap(prev)))
- 			return addr;
- 	}
- 
-@@ -2151,21 +2167,19 @@ find_vma_prev(struct mm_struct *mm, unsi
-  * update accounting. This is shared with both the
-  * grow-up and grow-down cases.
-  */
--static int acct_stack_growth(struct vm_area_struct *vma, unsigned long size, unsigned long grow)
-+static int acct_stack_growth(struct vm_area_struct *vma,
-+			     unsigned long size, unsigned long grow)
- {
- 	struct mm_struct *mm = vma->vm_mm;
- 	struct rlimit *rlim = current->signal->rlim;
--	unsigned long new_start, actual_size;
-+	unsigned long new_start;
- 
- 	/* address space limit tests */
- 	if (!may_expand_vm(mm, vma->vm_flags, grow))
- 		return -ENOMEM;
- 
- 	/* Stack limit test */
--	actual_size = size;
--	if (size && (vma->vm_flags & (VM_GROWSUP | VM_GROWSDOWN)))
--		actual_size -= PAGE_SIZE;
--	if (actual_size > READ_ONCE(rlim[RLIMIT_STACK].rlim_cur))
-+	if (size > READ_ONCE(rlim[RLIMIT_STACK].rlim_cur))
- 		return -ENOMEM;
- 
- 	/* mlock limit tests */
-@@ -2203,17 +2217,30 @@ static int acct_stack_growth(struct vm_a
- int expand_upwards(struct vm_area_struct *vma, unsigned long address)
- {
- 	struct mm_struct *mm = vma->vm_mm;
-+	struct vm_area_struct *next;
-+	unsigned long gap_addr;
- 	int error = 0;
- 
- 	if (!(vma->vm_flags & VM_GROWSUP))
- 		return -EFAULT;
- 
- 	/* Guard against wrapping around to address 0. */
--	if (address < PAGE_ALIGN(address+4))
--		address = PAGE_ALIGN(address+4);
--	else
-+	address &= PAGE_MASK;
-+	address += PAGE_SIZE;
-+	if (!address)
- 		return -ENOMEM;
- 
-+	/* Enforce stack_guard_gap */
-+	gap_addr = address + stack_guard_gap;
-+	if (gap_addr < address)
-+		return -ENOMEM;
-+	next = vma->vm_next;
-+	if (next && next->vm_start < gap_addr) {
-+		if (!(next->vm_flags & VM_GROWSUP))
-+			return -ENOMEM;
-+		/* Check that both stack segments have the same anon_vma? */
-+	}
-+
- 	/* We must make sure the anon_vma is allocated. */
- 	if (unlikely(anon_vma_prepare(vma)))
- 		return -ENOMEM;
-@@ -2257,7 +2284,7 @@ int expand_upwards(struct vm_area_struct
- 				if (vma->vm_next)
- 					vma_gap_update(vma->vm_next);
- 				else
--					mm->highest_vm_end = address;
-+					mm->highest_vm_end = vm_end_gap(vma);
- 				spin_unlock(&mm->page_table_lock);
- 
- 				perf_event_mmap(vma);
-@@ -2278,6 +2305,8 @@ int expand_downwards(struct vm_area_stru
- 				   unsigned long address)
- {
- 	struct mm_struct *mm = vma->vm_mm;
-+	struct vm_area_struct *prev;
-+	unsigned long gap_addr;
- 	int error;
- 
- 	address &= PAGE_MASK;
-@@ -2285,6 +2314,17 @@ int expand_downwards(struct vm_area_stru
- 	if (error)
- 		return error;
- 
-+	/* Enforce stack_guard_gap */
-+	gap_addr = address - stack_guard_gap;
-+	if (gap_addr > address)
-+		return -ENOMEM;
-+	prev = vma->vm_prev;
-+	if (prev && prev->vm_end > gap_addr) {
-+		if (!(prev->vm_flags & VM_GROWSDOWN))
-+			return -ENOMEM;
-+		/* Check that both stack segments have the same anon_vma? */
-+	}
-+
- 	/* We must make sure the anon_vma is allocated. */
- 	if (unlikely(anon_vma_prepare(vma)))
- 		return -ENOMEM;
-@@ -2339,28 +2379,25 @@ int expand_downwards(struct vm_area_stru
- 	return error;
- }
- 
--/*
-- * Note how expand_stack() refuses to expand the stack all the way to
-- * abut the next virtual mapping, *unless* that mapping itself is also
-- * a stack mapping. We want to leave room for a guard page, after all
-- * (the guard page itself is not added here, that is done by the
-- * actual page faulting logic)
-- *
-- * This matches the behavior of the guard page logic (see mm/memory.c:
-- * check_stack_guard_page()), which only allows the guard page to be
-- * removed under these circumstances.
-- */
-+/* enforced gap between the expanding stack and other mappings. */
-+unsigned long stack_guard_gap = 256UL<<PAGE_SHIFT;
-+
-+static int __init cmdline_parse_stack_guard_gap(char *p)
-+{
-+	unsigned long val;
-+	char *endptr;
-+
-+	val = simple_strtoul(p, &endptr, 10);
-+	if (!*endptr)
-+		stack_guard_gap = val << PAGE_SHIFT;
-+
-+	return 0;
-+}
-+__setup("stack_guard_gap=", cmdline_parse_stack_guard_gap);
-+
- #ifdef CONFIG_STACK_GROWSUP
- int expand_stack(struct vm_area_struct *vma, unsigned long address)
- {
--	struct vm_area_struct *next;
--
--	address &= PAGE_MASK;
--	next = vma->vm_next;
--	if (next && next->vm_start == address + PAGE_SIZE) {
--		if (!(next->vm_flags & VM_GROWSUP))
--			return -ENOMEM;
--	}
- 	return expand_upwards(vma, address);
- }
- 
-@@ -2382,14 +2419,6 @@ find_extend_vma(struct mm_struct *mm, un
- #else
- int expand_stack(struct vm_area_struct *vma, unsigned long address)
- {
--	struct vm_area_struct *prev;
--
--	address &= PAGE_MASK;
--	prev = vma->vm_prev;
--	if (prev && prev->vm_end == address) {
--		if (!(prev->vm_flags & VM_GROWSDOWN))
--			return -ENOMEM;
--	}
- 	return expand_downwards(vma, address);
- }
- 
-@@ -2487,7 +2516,7 @@ detach_vmas_to_be_unmapped(struct mm_str
- 		vma->vm_prev = prev;
- 		vma_gap_update(vma);
- 	} else
--		mm->highest_vm_end = prev ? prev->vm_end : 0;
-+		mm->highest_vm_end = prev ? vm_end_gap(prev) : 0;
- 	tail_vma->vm_next = NULL;
- 
- 	/* Kill the cache */