[PATCH RESEND 0/8] Fix mmap base in bottom-up mmap

[PATCH RESEND 0/8] Fix mmap base in bottom-up mmap

[Alexandre Ghiti]

This series fixes the fallback of the top-down mmap: in case of
failure, a bottom-up scheme can be tried as a last resort between
the top-down mmap base and the stack, hoping for a large unused stack
limit.

Lots of architectures and even mm code start this fallback
at TASK_UNMAPPED_BASE, which is useless since the top-down scheme
already failed on the whole address space: instead, simply use
mmap_base.

Along the way, it allows to get rid of of mmap_legacy_base and
mmap_compat_legacy_base from mm_struct.

Note that arm and mips already implement this behaviour. 

Alexandre Ghiti (8):
  s390: Start fallback of top-down mmap at mm->mmap_base
  sh: Start fallback of top-down mmap at mm->mmap_base
  sparc: Start fallback of top-down mmap at mm->mmap_base
  x86, hugetlbpage: Start fallback of top-down mmap at mm->mmap_base
  mm: Start fallback top-down mmap at mm->mmap_base
  parisc: Use mmap_base, not mmap_legacy_base, as low_limit for
    bottom-up mmap
  x86: Use mmap_*base, not mmap_*legacy_base, as low_limit for bottom-up
    mmap
  mm: Remove mmap_legacy_base and mmap_compat_legacy_code fields from
    mm_struct

 arch/parisc/kernel/sys_parisc.c  |  8 +++-----
 arch/s390/mm/mmap.c              |  2 +-
 arch/sh/mm/mmap.c                |  2 +-
 arch/sparc/kernel/sys_sparc_64.c |  2 +-
 arch/sparc/mm/hugetlbpage.c      |  2 +-
 arch/x86/include/asm/elf.h       |  2 +-
 arch/x86/kernel/sys_x86_64.c     |  4 ++--
 arch/x86/mm/hugetlbpage.c        |  7 ++++---
 arch/x86/mm/mmap.c               | 20 +++++++++-----------
 include/linux/mm_types.h         |  2 --
 mm/debug.c                       |  4 ++--
 mm/mmap.c                        |  2 +-
 12 files changed, 26 insertions(+), 31 deletions(-)

-- 
2.20.1

[PATCH RESEND 1/8] s390: Start fallback of top-down mmap at mm->mmap_base

[Alexandre Ghiti]

In case of mmap failure in top-down mode, there is no need to go through
the whole address space again for the bottom-up fallback: the goal of this
fallback is to find, as a last resort, space between the top-down mmap base
and the stack, which is the only place not covered by the top-down mmap.

Signed-off-by: Alexandre Ghiti <alex@ghiti.fr>
---
 arch/s390/mm/mmap.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/s390/mm/mmap.c b/arch/s390/mm/mmap.c
index cbc718ba6d78..4a222969843b 100644
--- a/arch/s390/mm/mmap.c
+++ b/arch/s390/mm/mmap.c
@@ -166,7 +166,7 @@ arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
 	if (addr & ~PAGE_MASK) {
 		VM_BUG_ON(addr != -ENOMEM);
 		info.flags = 0;
-		info.low_limit = TASK_UNMAPPED_BASE;
+		info.low_limit = mm->mmap_base;
 		info.high_limit = TASK_SIZE;
 		addr = vm_unmapped_area(&info);
 		if (addr & ~PAGE_MASK)
-- 
2.20.1

[PATCH RESEND 2/8] sh: Start fallback of top-down mmap at mm->mmap_base

[Alexandre Ghiti]

In case of mmap failure in top-down mode, there is no need to go through
the whole address space again for the bottom-up fallback: the goal of this
fallback is to find, as a last resort, space between the top-down mmap base
and the stack, which is the only place not covered by the top-down mmap.

Signed-off-by: Alexandre Ghiti <alex@ghiti.fr>
---
 arch/sh/mm/mmap.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/sh/mm/mmap.c b/arch/sh/mm/mmap.c
index 6a1a1297baae..4c7da92473dd 100644
--- a/arch/sh/mm/mmap.c
+++ b/arch/sh/mm/mmap.c
@@ -135,7 +135,7 @@ arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
 	if (addr & ~PAGE_MASK) {
 		VM_BUG_ON(addr != -ENOMEM);
 		info.flags = 0;
-		info.low_limit = TASK_UNMAPPED_BASE;
+		info.low_limit = mm->mmap_base;
 		info.high_limit = TASK_SIZE;
 		addr = vm_unmapped_area(&info);
 	}
-- 
2.20.1

[PATCH RESEND 3/8] sparc: Start fallback of top-down mmap at mm->mmap_base

[Alexandre Ghiti]

In case of mmap failure in top-down mode, there is no need to go through
the whole address space again for the bottom-up fallback: the goal of this
fallback is to find, as a last resort, space between the top-down mmap base
and the stack, which is the only place not covered by the top-down mmap.

Signed-off-by: Alexandre Ghiti <alex@ghiti.fr>
---
 arch/sparc/kernel/sys_sparc_64.c | 2 +-
 arch/sparc/mm/hugetlbpage.c      | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/sparc/kernel/sys_sparc_64.c b/arch/sparc/kernel/sys_sparc_64.c
index ccc88926bc00..ea1de1e5fa8d 100644
--- a/arch/sparc/kernel/sys_sparc_64.c
+++ b/arch/sparc/kernel/sys_sparc_64.c
@@ -206,7 +206,7 @@ arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
 	if (addr & ~PAGE_MASK) {
 		VM_BUG_ON(addr != -ENOMEM);
 		info.flags = 0;
-		info.low_limit = TASK_UNMAPPED_BASE;
+		info.low_limit = mm->mmap_base;
 		info.high_limit = STACK_TOP32;
 		addr = vm_unmapped_area(&info);
 	}
diff --git a/arch/sparc/mm/hugetlbpage.c b/arch/sparc/mm/hugetlbpage.c
index f78793a06bbd..9c67f805abc8 100644
--- a/arch/sparc/mm/hugetlbpage.c
+++ b/arch/sparc/mm/hugetlbpage.c
@@ -86,7 +86,7 @@ hugetlb_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
 	if (addr & ~PAGE_MASK) {
 		VM_BUG_ON(addr != -ENOMEM);
 		info.flags = 0;
-		info.low_limit = TASK_UNMAPPED_BASE;
+		info.low_limit = mm->mmap_base;
 		info.high_limit = STACK_TOP32;
 		addr = vm_unmapped_area(&info);
 	}
-- 
2.20.1

[PATCH RESEND 4/8] x86, hugetlbpage: Start fallback of top-down mmap at mm->mmap_base

[Alexandre Ghiti]

In case of mmap failure in top-down mode, there is no need to go through
the whole address space again for the bottom-up fallback: the goal of this
fallback is to find, as a last resort, space between the top-down mmap base
and the stack, which is the only place not covered by the top-down mmap.

Signed-off-by: Alexandre Ghiti <alex@ghiti.fr>
---
 arch/x86/mm/hugetlbpage.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/arch/x86/mm/hugetlbpage.c b/arch/x86/mm/hugetlbpage.c
index fab095362c50..4b90339aef50 100644
--- a/arch/x86/mm/hugetlbpage.c
+++ b/arch/x86/mm/hugetlbpage.c
@@ -106,11 +106,12 @@ static unsigned long hugetlb_get_unmapped_area_topdown(struct file *file,
 {
 	struct hstate *h = hstate_file(file);
 	struct vm_unmapped_area_info info;
+	unsigned long mmap_base = get_mmap_base(0);
 
 	info.flags = VM_UNMAPPED_AREA_TOPDOWN;
 	info.length = len;
 	info.low_limit = PAGE_SIZE;
-	info.high_limit = get_mmap_base(0);
+	info.high_limit = mmap_base;
 
 	/*
 	 * If hint address is above DEFAULT_MAP_WINDOW, look for unmapped area
@@ -132,7 +133,7 @@ static unsigned long hugetlb_get_unmapped_area_topdown(struct file *file,
 	if (addr & ~PAGE_MASK) {
 		VM_BUG_ON(addr != -ENOMEM);
 		info.flags = 0;
-		info.low_limit = TASK_UNMAPPED_BASE;
+		info.low_limit = mmap_base;
 		info.high_limit = TASK_SIZE_LOW;
 		addr = vm_unmapped_area(&info);
 	}
-- 
2.20.1

[PATCH RESEND 5/8] mm: Start fallback top-down mmap at mm->mmap_base

[Alexandre Ghiti]

In case of mmap failure in top-down mode, there is no need to go through
the whole address space again for the bottom-up fallback: the goal of this
fallback is to find, as a last resort, space between the top-down mmap base
and the stack, which is the only place not covered by the top-down mmap.

Signed-off-by: Alexandre Ghiti <alex@ghiti.fr>
---
 mm/mmap.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mm/mmap.c b/mm/mmap.c
index dedae10cb6e2..e563145c1ff4 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -2185,7 +2185,7 @@ arch_get_unmapped_area_topdown(struct file *filp, unsigned long addr,
 	if (offset_in_page(addr)) {
 		VM_BUG_ON(addr != -ENOMEM);
 		info.flags = 0;
-		info.low_limit = TASK_UNMAPPED_BASE;
+		info.low_limit = arch_get_mmap_base(addr, mm->mmap_base);
 		info.high_limit = mmap_end;
 		addr = vm_unmapped_area(&info);
 	}
-- 
2.20.1

[PATCH RESEND 6/8] parisc: Use mmap_base, not mmap_legacy_base, as low_limit for bottom-up mmap

[Alexandre Ghiti]

Bottom-up mmap scheme is used twice:

- for legacy mode, in which mmap_legacy_base and mmap_base are equal.

- in case of mmap failure in top-down mode, where there is no need to go
through the whole address space again for the bottom-up fallback: the goal
of this fallback is to find, as a last resort, space between the top-down
mmap base and the stack, which is the only place not covered by the
top-down mmap.

Then this commit removes the usage of mmap_legacy_base field from parisc
code.

Signed-off-by: Alexandre Ghiti <alex@ghiti.fr>
---
 arch/parisc/kernel/sys_parisc.c | 8 +++-----
 1 file changed, 3 insertions(+), 5 deletions(-)

diff --git a/arch/parisc/kernel/sys_parisc.c b/arch/parisc/kernel/sys_parisc.c
index 5d458a44b09c..e987f3a8eb0b 100644
--- a/arch/parisc/kernel/sys_parisc.c
+++ b/arch/parisc/kernel/sys_parisc.c
@@ -119,7 +119,7 @@ unsigned long arch_get_unmapped_area(struct file *filp, unsigned long addr,
 
 	info.flags = 0;
 	info.length = len;
-	info.low_limit = mm->mmap_legacy_base;
+	info.low_limit = mm->mmap_base;
 	info.high_limit = mmap_upper_limit(NULL);
 	info.align_mask = last_mmap ? (PAGE_MASK & (SHM_COLOUR - 1)) : 0;
 	info.align_offset = shared_align_offset(last_mmap, pgoff);
@@ -240,13 +240,11 @@ static unsigned long mmap_legacy_base(void)
  */
 void arch_pick_mmap_layout(struct mm_struct *mm, struct rlimit *rlim_stack)
 {
-	mm->mmap_legacy_base = mmap_legacy_base();
-	mm->mmap_base = mmap_upper_limit(rlim_stack);
-
 	if (mmap_is_legacy()) {
-		mm->mmap_base = mm->mmap_legacy_base;
+		mm->mmap_base = mmap_legacy_base();
 		mm->get_unmapped_area = arch_get_unmapped_area;
 	} else {
+		mm->mmap_base = mmap_upper_limit(rlim_stack);
 		mm->get_unmapped_area = arch_get_unmapped_area_topdown;
 	}
 }
-- 
2.20.1

[PATCH RESEND 7/8] x86: Use mmap_*base, not mmap_*legacy_base, as low_limit for bottom-up mmap

[Alexandre Ghiti]

Bottom-up mmap scheme is used twice:

- for legacy mode, in which mmap_legacy_base and mmap_compat_legacy_base
are respectively equal to mmap_base and mmap_compat_base.

- in case of mmap failure in top-down mode, where there is no need to go
through the whole address space again for the bottom-up fallback: the goal
of this fallback is to find, as a last resort, space between the top-down
mmap base and the stack, which is the only place not covered by the
top-down mmap.

Then this commit removes the usage of mmap_legacy_base and
mmap_compat_legacy_base fields from x86 code.

Signed-off-by: Alexandre Ghiti <alex@ghiti.fr>
---
 arch/x86/include/asm/elf.h   |  2 +-
 arch/x86/kernel/sys_x86_64.c |  4 ++--
 arch/x86/mm/hugetlbpage.c    |  4 ++--
 arch/x86/mm/mmap.c           | 20 +++++++++-----------
 4 files changed, 14 insertions(+), 16 deletions(-)

diff --git a/arch/x86/include/asm/elf.h b/arch/x86/include/asm/elf.h
index 69c0f892e310..bbfd81453250 100644
--- a/arch/x86/include/asm/elf.h
+++ b/arch/x86/include/asm/elf.h
@@ -307,7 +307,7 @@ static inline int mmap_is_ia32(void)
 
 extern unsigned long task_size_32bit(void);
 extern unsigned long task_size_64bit(int full_addr_space);
-extern unsigned long get_mmap_base(int is_legacy);
+extern unsigned long get_mmap_base(void);
 extern bool mmap_address_hint_valid(unsigned long addr, unsigned long len);
 
 #ifdef CONFIG_X86_32
diff --git a/arch/x86/kernel/sys_x86_64.c b/arch/x86/kernel/sys_x86_64.c
index f7476ce23b6e..0bf8604bea5e 100644
--- a/arch/x86/kernel/sys_x86_64.c
+++ b/arch/x86/kernel/sys_x86_64.c
@@ -121,7 +121,7 @@ static void find_start_end(unsigned long addr, unsigned long flags,
 		return;
 	}
 
-	*begin	= get_mmap_base(1);
+	*begin	= get_mmap_base();
 	if (in_32bit_syscall())
 		*end = task_size_32bit();
 	else
@@ -211,7 +211,7 @@ arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
 	info.flags = VM_UNMAPPED_AREA_TOPDOWN;
 	info.length = len;
 	info.low_limit = PAGE_SIZE;
-	info.high_limit = get_mmap_base(0);
+	info.high_limit = get_mmap_base();
 
 	/*
 	 * If hint address is above DEFAULT_MAP_WINDOW, look for unmapped area
diff --git a/arch/x86/mm/hugetlbpage.c b/arch/x86/mm/hugetlbpage.c
index 4b90339aef50..3a7f11e66114 100644
--- a/arch/x86/mm/hugetlbpage.c
+++ b/arch/x86/mm/hugetlbpage.c
@@ -86,7 +86,7 @@ static unsigned long hugetlb_get_unmapped_area_bottomup(struct file *file,
 
 	info.flags = 0;
 	info.length = len;
-	info.low_limit = get_mmap_base(1);
+	info.low_limit = get_mmap_base();
 
 	/*
 	 * If hint address is above DEFAULT_MAP_WINDOW, look for unmapped area
@@ -106,7 +106,7 @@ static unsigned long hugetlb_get_unmapped_area_topdown(struct file *file,
 {
 	struct hstate *h = hstate_file(file);
 	struct vm_unmapped_area_info info;
-	unsigned long mmap_base = get_mmap_base(0);
+	unsigned long mmap_base = get_mmap_base();
 
 	info.flags = VM_UNMAPPED_AREA_TOPDOWN;
 	info.length = len;
diff --git a/arch/x86/mm/mmap.c b/arch/x86/mm/mmap.c
index aae9a933dfd4..54c9ff301323 100644
--- a/arch/x86/mm/mmap.c
+++ b/arch/x86/mm/mmap.c
@@ -113,13 +113,12 @@ static unsigned long mmap_legacy_base(unsigned long rnd,
  * This function, called very early during the creation of a new
  * process VM image, sets up which VM layout function to use:
  */
-static void arch_pick_mmap_base(unsigned long *base, unsigned long *legacy_base,
+static void arch_pick_mmap_base(unsigned long *base,
 		unsigned long random_factor, unsigned long task_size,
 		struct rlimit *rlim_stack)
 {
-	*legacy_base = mmap_legacy_base(random_factor, task_size);
 	if (mmap_is_legacy())
-		*base = *legacy_base;
+		*base = mmap_legacy_base(random_factor, task_size);
 	else
 		*base = mmap_base(random_factor, task_size, rlim_stack);
 }
@@ -131,7 +130,7 @@ void arch_pick_mmap_layout(struct mm_struct *mm, struct rlimit *rlim_stack)
 	else
 		mm->get_unmapped_area = arch_get_unmapped_area_topdown;
 
-	arch_pick_mmap_base(&mm->mmap_base, &mm->mmap_legacy_base,
+	arch_pick_mmap_base(&mm->mmap_base,
 			arch_rnd(mmap64_rnd_bits), task_size_64bit(0),
 			rlim_stack);
 
@@ -142,23 +141,22 @@ void arch_pick_mmap_layout(struct mm_struct *mm, struct rlimit *rlim_stack)
 	 * applications and 32bit applications. The 64bit syscall uses
 	 * mmap_base, the compat syscall uses mmap_compat_base.
 	 */
-	arch_pick_mmap_base(&mm->mmap_compat_base, &mm->mmap_compat_legacy_base,
+	arch_pick_mmap_base(&mm->mmap_compat_base,
 			arch_rnd(mmap32_rnd_bits), task_size_32bit(),
 			rlim_stack);
 #endif
 }
 
-unsigned long get_mmap_base(int is_legacy)
+unsigned long get_mmap_base(void)
 {
 	struct mm_struct *mm = current->mm;
 
 #ifdef CONFIG_HAVE_ARCH_COMPAT_MMAP_BASES
-	if (in_32bit_syscall()) {
-		return is_legacy ? mm->mmap_compat_legacy_base
-				 : mm->mmap_compat_base;
-	}
+	if (in_32bit_syscall())
+		return mm->mmap_compat_base;
 #endif
-	return is_legacy ? mm->mmap_legacy_base : mm->mmap_base;
+
+	return mm->mmap_base;
 }
 
 const char *arch_vma_name(struct vm_area_struct *vma)
-- 
2.20.1

[PATCH RESEND 8/8] mm: Remove mmap_legacy_base and mmap_compat_legacy_code fields from mm_struct

[Alexandre Ghiti]

Now that x86 and parisc do not use those fields anymore, remove them from
mm code.

Signed-off-by: Alexandre Ghiti <alex@ghiti.fr>
---
 include/linux/mm_types.h | 2 --
 mm/debug.c               | 4 ++--
 2 files changed, 2 insertions(+), 4 deletions(-)

diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
index 1d1093474c1a..9a5935f9cc7e 100644
--- a/include/linux/mm_types.h
+++ b/include/linux/mm_types.h
@@ -364,11 +364,9 @@ struct mm_struct {
 				unsigned long pgoff, unsigned long flags);
 #endif
 		unsigned long mmap_base;	/* base of mmap area */
-		unsigned long mmap_legacy_base;	/* base of mmap area in bottom-up allocations */
 #ifdef CONFIG_HAVE_ARCH_COMPAT_MMAP_BASES
 		/* Base adresses for compatible mmap() */
 		unsigned long mmap_compat_base;
-		unsigned long mmap_compat_legacy_base;
 #endif
 		unsigned long task_size;	/* size of task vm space */
 		unsigned long highest_vm_end;	/* highest vma end address */
diff --git a/mm/debug.c b/mm/debug.c
index 8345bb6e4769..3ddffe1efcda 100644
--- a/mm/debug.c
+++ b/mm/debug.c
@@ -134,7 +134,7 @@ void dump_mm(const struct mm_struct *mm)
 #ifdef CONFIG_MMU
 		"get_unmapped_area %px\n"
 #endif
-		"mmap_base %lu mmap_legacy_base %lu highest_vm_end %lu\n"
+		"mmap_base %lu highest_vm_end %lu\n"
 		"pgd %px mm_users %d mm_count %d pgtables_bytes %lu map_count %d\n"
 		"hiwater_rss %lx hiwater_vm %lx total_vm %lx locked_vm %lx\n"
 		"pinned_vm %llx data_vm %lx exec_vm %lx stack_vm %lx\n"
@@ -162,7 +162,7 @@ void dump_mm(const struct mm_struct *mm)
 #ifdef CONFIG_MMU
 		mm->get_unmapped_area,
 #endif
-		mm->mmap_base, mm->mmap_legacy_base, mm->highest_vm_end,
+		mm->mmap_base, mm->highest_vm_end,
 		mm->pgd, atomic_read(&mm->mm_users),
 		atomic_read(&mm->mm_count),
 		mm_pgtables_bytes(mm),
-- 
2.20.1

Re: [PATCH RESEND 6/8] parisc: Use mmap_base, not mmap_legacy_base, as low_limit for bottom-up mmap

[Helge Deller]

On 20.06.19 07:03, Alexandre Ghiti wrote:
> Bottom-up mmap scheme is used twice:
>
> - for legacy mode, in which mmap_legacy_base and mmap_base are equal.
>
> - in case of mmap failure in top-down mode, where there is no need to go
> through the whole address space again for the bottom-up fallback: the goal
> of this fallback is to find, as a last resort, space between the top-down
> mmap base and the stack, which is the only place not covered by the
> top-down mmap.
>
> Then this commit removes the usage of mmap_legacy_base field from parisc
> code.
>
> Signed-off-by: Alexandre Ghiti <alex@ghiti.fr>

Boot-tested on parisc and seems to work nicely, thus:

Acked-by: Helge Deller <deller@gmx.de>

Helge



> ---
>  arch/parisc/kernel/sys_parisc.c | 8 +++-----
>  1 file changed, 3 insertions(+), 5 deletions(-)
>
> diff --git a/arch/parisc/kernel/sys_parisc.c b/arch/parisc/kernel/sys_parisc.c
> index 5d458a44b09c..e987f3a8eb0b 100644
> --- a/arch/parisc/kernel/sys_parisc.c
> +++ b/arch/parisc/kernel/sys_parisc.c
> @@ -119,7 +119,7 @@ unsigned long arch_get_unmapped_area(struct file *filp, unsigned long addr,
>
>  	info.flags = 0;
>  	info.length = len;
> -	info.low_limit = mm->mmap_legacy_base;
> +	info.low_limit = mm->mmap_base;
>  	info.high_limit = mmap_upper_limit(NULL);
>  	info.align_mask = last_mmap ? (PAGE_MASK & (SHM_COLOUR - 1)) : 0;
>  	info.align_offset = shared_align_offset(last_mmap, pgoff);
> @@ -240,13 +240,11 @@ static unsigned long mmap_legacy_base(void)
>   */
>  void arch_pick_mmap_layout(struct mm_struct *mm, struct rlimit *rlim_stack)
>  {
> -	mm->mmap_legacy_base = mmap_legacy_base();
> -	mm->mmap_base = mmap_upper_limit(rlim_stack);
> -
>  	if (mmap_is_legacy()) {
> -		mm->mmap_base = mm->mmap_legacy_base;
> +		mm->mmap_base = mmap_legacy_base();
>  		mm->get_unmapped_area = arch_get_unmapped_area;
>  	} else {
> +		mm->mmap_base = mmap_upper_limit(rlim_stack);
>  		mm->get_unmapped_area = arch_get_unmapped_area_topdown;
>  	}
>  }
>

Re: [PATCH RESEND 6/8] parisc: Use mmap_base, not mmap_legacy_base, as low_limit for bottom-up mmap

[Alex Ghiti]

On 6/25/19 10:09 AM, Helge Deller wrote:
> On 20.06.19 07:03, Alexandre Ghiti wrote:
>> Bottom-up mmap scheme is used twice:
>>
>> - for legacy mode, in which mmap_legacy_base and mmap_base are equal.
>>
>> - in case of mmap failure in top-down mode, where there is no need to go
>> through the whole address space again for the bottom-up fallback: the goal
>> of this fallback is to find, as a last resort, space between the top-down
>> mmap base and the stack, which is the only place not covered by the
>> top-down mmap.
>>
>> Then this commit removes the usage of mmap_legacy_base field from parisc
>> code.
>>
>> Signed-off-by: Alexandre Ghiti <alex@ghiti.fr>
> Boot-tested on parisc and seems to work nicely, thus:
>
> Acked-by: Helge Deller <deller@gmx.de>

Thanks Helge,

Alex

>
> Helge
>
>
>
>> ---
>>   arch/parisc/kernel/sys_parisc.c | 8 +++-----
>>   1 file changed, 3 insertions(+), 5 deletions(-)
>>
>> diff --git a/arch/parisc/kernel/sys_parisc.c b/arch/parisc/kernel/sys_parisc.c
>> index 5d458a44b09c..e987f3a8eb0b 100644
>> --- a/arch/parisc/kernel/sys_parisc.c
>> +++ b/arch/parisc/kernel/sys_parisc.c
>> @@ -119,7 +119,7 @@ unsigned long arch_get_unmapped_area(struct file *filp, unsigned long addr,
>>
>>   	info.flags = 0;
>>   	info.length = len;
>> -	info.low_limit = mm->mmap_legacy_base;
>> +	info.low_limit = mm->mmap_base;
>>   	info.high_limit = mmap_upper_limit(NULL);
>>   	info.align_mask = last_mmap ? (PAGE_MASK & (SHM_COLOUR - 1)) : 0;
>>   	info.align_offset = shared_align_offset(last_mmap, pgoff);
>> @@ -240,13 +240,11 @@ static unsigned long mmap_legacy_base(void)
>>    */
>>   void arch_pick_mmap_layout(struct mm_struct *mm, struct rlimit *rlim_stack)
>>   {
>> -	mm->mmap_legacy_base = mmap_legacy_base();
>> -	mm->mmap_base = mmap_upper_limit(rlim_stack);
>> -
>>   	if (mmap_is_legacy()) {
>> -		mm->mmap_base = mm->mmap_legacy_base;
>> +		mm->mmap_base = mmap_legacy_base();
>>   		mm->get_unmapped_area = arch_get_unmapped_area;
>>   	} else {
>> +		mm->mmap_base = mmap_upper_limit(rlim_stack);
>>   		mm->get_unmapped_area = arch_get_unmapped_area_topdown;
>>   	}
>>   }
>>

Re: [PATCH RESEND 0/8] Fix mmap base in bottom-up mmap

[Alexandre Ghiti]

On 6/20/19 7:03 AM, Alexandre Ghiti wrote:
> This series fixes the fallback of the top-down mmap: in case of
> failure, a bottom-up scheme can be tried as a last resort between
> the top-down mmap base and the stack, hoping for a large unused stack
> limit.
>
> Lots of architectures and even mm code start this fallback
> at TASK_UNMAPPED_BASE, which is useless since the top-down scheme
> already failed on the whole address space: instead, simply use
> mmap_base.
>
> Along the way, it allows to get rid of of mmap_legacy_base and
> mmap_compat_legacy_base from mm_struct.
>
> Note that arm and mips already implement this behaviour.
>
> Alexandre Ghiti (8):
>    s390: Start fallback of top-down mmap at mm->mmap_base
>    sh: Start fallback of top-down mmap at mm->mmap_base
>    sparc: Start fallback of top-down mmap at mm->mmap_base
>    x86, hugetlbpage: Start fallback of top-down mmap at mm->mmap_base
>    mm: Start fallback top-down mmap at mm->mmap_base
>    parisc: Use mmap_base, not mmap_legacy_base, as low_limit for
>      bottom-up mmap
>    x86: Use mmap_*base, not mmap_*legacy_base, as low_limit for bottom-up
>      mmap
>    mm: Remove mmap_legacy_base and mmap_compat_legacy_code fields from
>      mm_struct
>
>   arch/parisc/kernel/sys_parisc.c  |  8 +++-----
>   arch/s390/mm/mmap.c              |  2 +-
>   arch/sh/mm/mmap.c                |  2 +-
>   arch/sparc/kernel/sys_sparc_64.c |  2 +-
>   arch/sparc/mm/hugetlbpage.c      |  2 +-
>   arch/x86/include/asm/elf.h       |  2 +-
>   arch/x86/kernel/sys_x86_64.c     |  4 ++--
>   arch/x86/mm/hugetlbpage.c        |  7 ++++---
>   arch/x86/mm/mmap.c               | 20 +++++++++-----------
>   include/linux/mm_types.h         |  2 --
>   mm/debug.c                       |  4 ++--
>   mm/mmap.c                        |  2 +-
>   12 files changed, 26 insertions(+), 31 deletions(-)
>

Hi everyone,

This is just a preparatory series for the merging of x86 mmap top-down 
functions with
the generic ones (those should get into v5.3), if you could take some 
time to take a look,
that would be great :)

Thanks,

Alex

Re: [PATCH RESEND 0/8] Fix mmap base in bottom-up mmap

[Alexandre Ghiti]

On 6/20/19 7:03 AM, Alexandre Ghiti wrote:
> This series fixes the fallback of the top-down mmap: in case of
> failure, a bottom-up scheme can be tried as a last resort between
> the top-down mmap base and the stack, hoping for a large unused stack
> limit.
>
> Lots of architectures and even mm code start this fallback
> at TASK_UNMAPPED_BASE, which is useless since the top-down scheme
> already failed on the whole address space: instead, simply use
> mmap_base.
>
> Along the way, it allows to get rid of of mmap_legacy_base and
> mmap_compat_legacy_base from mm_struct.
>
> Note that arm and mips already implement this behaviour.
>
> Alexandre Ghiti (8):
>    s390: Start fallback of top-down mmap at mm->mmap_base
>    sh: Start fallback of top-down mmap at mm->mmap_base
>    sparc: Start fallback of top-down mmap at mm->mmap_base
>    x86, hugetlbpage: Start fallback of top-down mmap at mm->mmap_base
>    mm: Start fallback top-down mmap at mm->mmap_base
>    parisc: Use mmap_base, not mmap_legacy_base, as low_limit for
>      bottom-up mmap
>    x86: Use mmap_*base, not mmap_*legacy_base, as low_limit for bottom-up
>      mmap
>    mm: Remove mmap_legacy_base and mmap_compat_legacy_code fields from
>      mm_struct
>
>   arch/parisc/kernel/sys_parisc.c  |  8 +++-----
>   arch/s390/mm/mmap.c              |  2 +-
>   arch/sh/mm/mmap.c                |  2 +-
>   arch/sparc/kernel/sys_sparc_64.c |  2 +-
>   arch/sparc/mm/hugetlbpage.c      |  2 +-
>   arch/x86/include/asm/elf.h       |  2 +-
>   arch/x86/kernel/sys_x86_64.c     |  4 ++--
>   arch/x86/mm/hugetlbpage.c        |  7 ++++---
>   arch/x86/mm/mmap.c               | 20 +++++++++-----------
>   include/linux/mm_types.h         |  2 --
>   mm/debug.c                       |  4 ++--
>   mm/mmap.c                        |  2 +-
>   12 files changed, 26 insertions(+), 31 deletions(-)
>

Hi everyone,

Any thoughts about that series ? As said before, this is just a 
preparatory patchset in order to
merge x86 mmap top down code with the generic version.

Thanks for taking a look,

Alex

Re: [PATCH RESEND 0/8] Fix mmap base in bottom-up mmap

[Helge Deller]

On 26.08.19 09:34, Alexandre Ghiti wrote:
> On 6/20/19 7:03 AM, Alexandre Ghiti wrote:
>> This series fixes the fallback of the top-down mmap: in case of
>> failure, a bottom-up scheme can be tried as a last resort between
>> the top-down mmap base and the stack, hoping for a large unused stack
>> limit.
>>
>> Lots of architectures and even mm code start this fallback
>> at TASK_UNMAPPED_BASE, which is useless since the top-down scheme
>> already failed on the whole address space: instead, simply use
>> mmap_base.
>>
>> Along the way, it allows to get rid of of mmap_legacy_base and
>> mmap_compat_legacy_base from mm_struct.
>>
>> Note that arm and mips already implement this behaviour.
>>
>> Alexandre Ghiti (8):
>>    s390: Start fallback of top-down mmap at mm->mmap_base
>>    sh: Start fallback of top-down mmap at mm->mmap_base
>>    sparc: Start fallback of top-down mmap at mm->mmap_base
>>    x86, hugetlbpage: Start fallback of top-down mmap at mm->mmap_base
>>    mm: Start fallback top-down mmap at mm->mmap_base
>>    parisc: Use mmap_base, not mmap_legacy_base, as low_limit for
>>      bottom-up mmap
>>    x86: Use mmap_*base, not mmap_*legacy_base, as low_limit for bottom-up
>>      mmap
>>    mm: Remove mmap_legacy_base and mmap_compat_legacy_code fields from
>>      mm_struct
>>
>>   arch/parisc/kernel/sys_parisc.c  |  8 +++-----
>>   arch/s390/mm/mmap.c              |  2 +-
>>   arch/sh/mm/mmap.c                |  2 +-
>>   arch/sparc/kernel/sys_sparc_64.c |  2 +-
>>   arch/sparc/mm/hugetlbpage.c      |  2 +-
>>   arch/x86/include/asm/elf.h       |  2 +-
>>   arch/x86/kernel/sys_x86_64.c     |  4 ++--
>>   arch/x86/mm/hugetlbpage.c        |  7 ++++---
>>   arch/x86/mm/mmap.c               | 20 +++++++++-----------
>>   include/linux/mm_types.h         |  2 --
>>   mm/debug.c                       |  4 ++--
>>   mm/mmap.c                        |  2 +-
>>   12 files changed, 26 insertions(+), 31 deletions(-)
>>
>
> Any thoughts about that series ? As said before, this is just a preparatory patchset in order to
> merge x86 mmap top down code with the generic version.

I just tested your patch series successfully on the parisc
architeture. You may add:

Tested-by: Helge Deller <deller@gmx.de> # parisc

Thanks!
Helge

Re: [PATCH RESEND 0/8] Fix mmap base in bottom-up mmap

[Alex Ghiti]

On 8/26/19 6:37 PM, Helge Deller wrote:
> On 26.08.19 09:34, Alexandre Ghiti wrote:
>> On 6/20/19 7:03 AM, Alexandre Ghiti wrote:
>>> This series fixes the fallback of the top-down mmap: in case of
>>> failure, a bottom-up scheme can be tried as a last resort between
>>> the top-down mmap base and the stack, hoping for a large unused stack
>>> limit.
>>>
>>> Lots of architectures and even mm code start this fallback
>>> at TASK_UNMAPPED_BASE, which is useless since the top-down scheme
>>> already failed on the whole address space: instead, simply use
>>> mmap_base.
>>>
>>> Along the way, it allows to get rid of of mmap_legacy_base and
>>> mmap_compat_legacy_base from mm_struct.
>>>
>>> Note that arm and mips already implement this behaviour.
>>>
>>> Alexandre Ghiti (8):
>>>    s390: Start fallback of top-down mmap at mm->mmap_base
>>>    sh: Start fallback of top-down mmap at mm->mmap_base
>>>    sparc: Start fallback of top-down mmap at mm->mmap_base
>>>    x86, hugetlbpage: Start fallback of top-down mmap at mm->mmap_base
>>>    mm: Start fallback top-down mmap at mm->mmap_base
>>>    parisc: Use mmap_base, not mmap_legacy_base, as low_limit for
>>>      bottom-up mmap
>>>    x86: Use mmap_*base, not mmap_*legacy_base, as low_limit for 
>>> bottom-up
>>>      mmap
>>>    mm: Remove mmap_legacy_base and mmap_compat_legacy_code fields from
>>>      mm_struct
>>>
>>>   arch/parisc/kernel/sys_parisc.c  |  8 +++-----
>>>   arch/s390/mm/mmap.c              |  2 +-
>>>   arch/sh/mm/mmap.c                |  2 +-
>>>   arch/sparc/kernel/sys_sparc_64.c |  2 +-
>>>   arch/sparc/mm/hugetlbpage.c      |  2 +-
>>>   arch/x86/include/asm/elf.h       |  2 +-
>>>   arch/x86/kernel/sys_x86_64.c     |  4 ++--
>>>   arch/x86/mm/hugetlbpage.c        |  7 ++++---
>>>   arch/x86/mm/mmap.c               | 20 +++++++++-----------
>>>   include/linux/mm_types.h         |  2 --
>>>   mm/debug.c                       |  4 ++--
>>>   mm/mmap.c                        |  2 +-
>>>   12 files changed, 26 insertions(+), 31 deletions(-)
>>>
>>
>> Any thoughts about that series ? As said before, this is just a 
>> preparatory patchset in order to
>> merge x86 mmap top down code with the generic version.
>
> I just tested your patch series successfully on the parisc
> architeture. You may add:
>
> Tested-by: Helge Deller <deller@gmx.de> # parisc

Thanks again Helge !

Alex


>
> Thanks!
> Helge

[PATCH RESEND 0/8] Fix mmap base in bottom-up mmap

[Alexandre Ghiti]

This series fixes the fallback of the top-down mmap: in case of
failure, a bottom-up scheme can be tried as a last resort between
the top-down mmap base and the stack, hoping for a large unused stack
limit.

Lots of architectures and even mm code start this fallback
at TASK_UNMAPPED_BASE, which is useless since the top-down scheme
already failed on the whole address space: instead, simply use
mmap_base.

Along the way, it allows to get rid of of mmap_legacy_base and
mmap_compat_legacy_base from mm_struct.

Note that arm and mips already implement this behaviour.  

Alexandre Ghiti (8):
  s390: Start fallback of top-down mmap at mm->mmap_base
  sh: Start fallback of top-down mmap at mm->mmap_base
  sparc: Start fallback of top-down mmap at mm->mmap_base
  x86, hugetlbpage: Start fallback of top-down mmap at mm->mmap_base
  mm: Start fallback top-down mmap at mm->mmap_base
  parisc: Use mmap_base, not mmap_legacy_base, as low_limit for
    bottom-up mmap
  x86: Use mmap_*base, not mmap_*legacy_base, as low_limit for bottom-up
    mmap
  mm: Remove mmap_legacy_base and mmap_compat_legacy_code fields from
    mm_struct

 arch/parisc/kernel/sys_parisc.c  |  8 +++-----
 arch/s390/mm/mmap.c              |  2 +-
 arch/sh/mm/mmap.c                |  2 +-
 arch/sparc/kernel/sys_sparc_64.c |  2 +-
 arch/sparc/mm/hugetlbpage.c      |  2 +-
 arch/x86/include/asm/elf.h       |  2 +-
 arch/x86/kernel/sys_x86_64.c     |  4 ++--
 arch/x86/mm/hugetlbpage.c        |  7 ++++---
 arch/x86/mm/mmap.c               | 20 +++++++++-----------
 include/linux/mm_types.h         |  2 --
 mm/debug.c                       |  4 ++--
 mm/mmap.c                        |  2 +-
 12 files changed, 26 insertions(+), 31 deletions(-)

-- 
2.20.1

[PATCH RESEND 0/8] Fix mmap base in bottom-up mmap

[Alexandre Ghiti]

(Sorry for the previous interrupted series) 

This series fixes the fallback of the top-down mmap: in case of
failure, a bottom-up scheme can be tried as a last resort between
the top-down mmap base and the stack, hoping for a large unused stack
limit.

Lots of architectures and even mm code start this fallback
at TASK_UNMAPPED_BASE, which is useless since the top-down scheme
already failed on the whole address space: instead, simply use
mmap_base.

Along the way, it allows to get rid of of mmap_legacy_base and
mmap_compat_legacy_base from mm_struct.

Note that arm and mips already implement this behaviour.

Alexandre Ghiti (8):
  s390: Start fallback of top-down mmap at mm->mmap_base
  sh: Start fallback of top-down mmap at mm->mmap_base
  sparc: Start fallback of top-down mmap at mm->mmap_base
  x86, hugetlbpage: Start fallback of top-down mmap at mm->mmap_base
  mm: Start fallback top-down mmap at mm->mmap_base
  parisc: Use mmap_base, not mmap_legacy_base, as low_limit for
    bottom-up mmap
  x86: Use mmap_*base, not mmap_*legacy_base, as low_limit for bottom-up
    mmap
  mm: Remove mmap_legacy_base and mmap_compat_legacy_code fields from
    mm_struct

 arch/parisc/kernel/sys_parisc.c  |  8 +++-----
 arch/s390/mm/mmap.c              |  2 +-
 arch/sh/mm/mmap.c                |  2 +-
 arch/sparc/kernel/sys_sparc_64.c |  2 +-
 arch/sparc/mm/hugetlbpage.c      |  2 +-
 arch/x86/include/asm/elf.h       |  2 +-
 arch/x86/kernel/sys_x86_64.c     |  4 ++--
 arch/x86/mm/hugetlbpage.c        |  7 ++++---
 arch/x86/mm/mmap.c               | 20 +++++++++-----------
 include/linux/mm_types.h         |  2 --
 mm/debug.c                       |  4 ++--
 mm/mmap.c                        |  2 +-
 12 files changed, 26 insertions(+), 31 deletions(-)

-- 
2.20.1