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Message-ID: <d585f9e5-538e-bdab-c89b-b4e1cc03c7b2@suse.cz>
Date: Tue, 7 Dec 2021 19:01:14 +0100
From: Vlastimil Babka <vbabka@...e.cz>
To: Liam Howlett <liam.howlett@...cle.com>,
"maple-tree@...ts.infradead.org" <maple-tree@...ts.infradead.org>,
"linux-mm@...ck.org" <linux-mm@...ck.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
Andrew Morton <akpm@...ux-foundation.org>
Cc: Song Liu <songliubraving@...com>,
Davidlohr Bueso <dave@...olabs.net>,
"Paul E . McKenney" <paulmck@...nel.org>,
Matthew Wilcox <willy@...radead.org>,
Laurent Dufour <ldufour@...ux.ibm.com>,
David Rientjes <rientjes@...gle.com>,
Axel Rasmussen <axelrasmussen@...gle.com>,
Suren Baghdasaryan <surenb@...gle.com>,
Rik van Riel <riel@...riel.com>,
Peter Zijlstra <peterz@...radead.org>,
Michel Lespinasse <walken.cr@...il.com>,
Jerome Glisse <jglisse@...hat.com>,
Minchan Kim <minchan@...gle.com>,
Joel Fernandes <joelaf@...gle.com>,
Rom Lemarchand <romlem@...gle.com>
Subject: Re: [PATCH v4 06/66] mm: Start tracking VMAs with maple tree
On 12/1/21 15:29, Liam Howlett wrote:
> From: "Liam R. Howlett" <Liam.Howlett@...cle.com>
>
> Start tracking the VMAs with the new maple tree structure in parallel
> with the rb_tree. Add debug and trace events for maple tree operations
> and duplicate the rb_tree that is created on forks into the maple tree.
>
> The maple tree is added to the mm_struct including the mm_init struct,
> added support in required mm/mmap functions, added tracking in
> kernel/fork for process forking, and used to find the unmapped_area and
> checked against what the rbtree finds.
>
> Signed-off-by: Liam R. Howlett <Liam.Howlett@...cle.com>
> Signed-off-by: Matthew Wilcox (Oracle) <willy@...radead.org>
> ---
> arch/x86/kernel/tboot.c | 1 +
> drivers/firmware/efi/efi.c | 1 +
> include/linux/mm.h | 2 +
> include/linux/mm_types.h | 3 +
> include/trace/events/mmap.h | 71 ++++++++++++
> init/main.c | 2 +
> kernel/fork.c | 5 +
> mm/init-mm.c | 2 +
> mm/internal.h | 73 ++++++++++++
> mm/mmap.c | 220 +++++++++++++++++++++++++++++++++++-
> 10 files changed, 378 insertions(+), 2 deletions(-)
>
> diff --git a/arch/x86/kernel/tboot.c b/arch/x86/kernel/tboot.c
> index f9af561c3cd4..859e8d2ea070 100644
> --- a/arch/x86/kernel/tboot.c
> +++ b/arch/x86/kernel/tboot.c
> @@ -98,6 +98,7 @@ void __init tboot_probe(void)
> static pgd_t *tboot_pg_dir;
> static struct mm_struct tboot_mm = {
> .mm_rb = RB_ROOT,
> + .mm_mt = MTREE_INIT_EXT(mm_mt, MM_MT_FLAGS, tboot_mm.mmap_lock),
> .pgd = swapper_pg_dir,
> .mm_users = ATOMIC_INIT(2),
> .mm_count = ATOMIC_INIT(1),
> diff --git a/drivers/firmware/efi/efi.c b/drivers/firmware/efi/efi.c
> index ae79c3300129..0b40291416ca 100644
> --- a/drivers/firmware/efi/efi.c
> +++ b/drivers/firmware/efi/efi.c
> @@ -55,6 +55,7 @@ static unsigned long __initdata rt_prop = EFI_INVALID_TABLE_ADDR;
>
> struct mm_struct efi_mm = {
> .mm_rb = RB_ROOT,
> + .mm_mt = MTREE_INIT_EXT(mm_mt, MM_MT_FLAGS, efi_mm.mmap_lock),
> .mm_users = ATOMIC_INIT(2),
> .mm_count = ATOMIC_INIT(1),
> .write_protect_seq = SEQCNT_ZERO(efi_mm.write_protect_seq),
> diff --git a/include/linux/mm.h b/include/linux/mm.h
> index a7e4a9e7d807..9eae78a155be 100644
> --- a/include/linux/mm.h
> +++ b/include/linux/mm.h
> @@ -2610,6 +2610,8 @@ extern bool arch_has_descending_max_zone_pfns(void);
> /* nommu.c */
> extern atomic_long_t mmap_pages_allocated;
> extern int nommu_shrink_inode_mappings(struct inode *, size_t, size_t);
> +/* maple_tree */
Hm should it say mmap.c as that's where vma_store() is defined.
...
> diff --git a/mm/mmap.c b/mm/mmap.c
> index bfb0ea164a90..c2f1431886d4 100644
> --- a/mm/mmap.c
> +++ b/mm/mmap.c
...
> @@ -1901,12 +2018,21 @@ static unsigned long unmapped_area(struct vm_unmapped_area_info *info)
> struct mm_struct *mm = current->mm;
> struct vm_area_struct *vma;
> unsigned long length, low_limit, high_limit, gap_start, gap_end;
> + unsigned long gap;
> + MA_STATE(mas, &mm->mm_mt, 0, 0);
>
> /* Adjust search length to account for worst case alignment overhead */
> length = info->length + info->align_mask;
> if (length < info->length)
> return -ENOMEM;
>
> + rcu_read_lock();
> + mas_empty_area_rev(&mas, info->low_limit, info->high_limit - 1,
> + length);
unmapped_area_topdown also uses mas_empty_area_rev(), shouldn't this one be
non-rev()?
> + rcu_read_unlock();
> + gap = mas.index;
> + gap += (info->align_offset - gap) & info->align_mask;
> +
> /* Adjust search limits by the desired length */
> if (info->high_limit < length)
> return -ENOMEM;
> @@ -1988,20 +2114,39 @@ static unsigned long unmapped_area(struct vm_unmapped_area_info *info)
>
> VM_BUG_ON(gap_start + info->length > info->high_limit);
> VM_BUG_ON(gap_start + info->length > gap_end);
> +
> + VM_BUG_ON(gap != gap_start);
> return gap_start;
> }
>
> +static inline unsigned long top_area_aligned(struct vm_unmapped_area_info *info,
> + unsigned long end)
> +{
> + return (end - info->length - info->align_offset) & (~info->align_mask);
> +}
Looks like this is never used anywhere and just deleted later in the series.
> +
> static unsigned long unmapped_area_topdown(struct vm_unmapped_area_info *info)
> {
> struct mm_struct *mm = current->mm;
> - struct vm_area_struct *vma;
> + struct vm_area_struct *vma = NULL;
> unsigned long length, low_limit, high_limit, gap_start, gap_end;
> + unsigned long gap;
> +
> + MA_STATE(mas, &mm->mm_mt, 0, 0);
> + validate_mm_mt(mm);
>
> /* Adjust search length to account for worst case alignment overhead */
> length = info->length + info->align_mask;
> if (length < info->length)
> return -ENOMEM;
>
> + rcu_read_lock();
> + mas_empty_area_rev(&mas, info->low_limit, info->high_limit - 1,
> + length);
> + rcu_read_unlock();
> + gap = (mas.index + info->align_mask) & ~info->align_mask;
> + gap -= info->align_offset & info->align_mask;
> +
> /*
> * Adjust search limits by the desired length.
> * See implementation comment at top of unmapped_area().
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