qiurui
/
Centos-kernel-stream-9
mirror of https://gitlab.com/redhat/centos-stream/src/kernel/centos-stream-9.git
1
0
Fork 0
Code Issues Packages Projects Releases Wiki Activity

mm/mmap: move vma operations to mm_struct out of the critical section of file mapping lock 

JIRA: https://issues.redhat.com/browse/RHEL-27743
Conflicts:
  * merge conflict due to out-of-order backport for upstream commit
    ad9f006351c3 ("mm: always lock new vma before inserting into vma tree")
    (rhel commit 4263d177b8) wrongly folding part of the first hunk of
    this patch.

This patch is a backport of the following upstream commit:
commit 6852c46c783d20a4c0153d14d2990040e5e6e47e
Author: Yu Ma <yu.ma@intel.com>
Date:   Wed Jul 12 10:57:39 2023 -0400

    mm/mmap: move vma operations to mm_struct out of the critical section of file mapping lock

    UnixBench/Execl represents a class of workload where bash scripts are
    spawned frequently to do some short jobs.  When running multiple parallel
    tasks, hot osq_lock is observed from do_mmap and exit_mmap.  Both of them
    come from load_elf_binary through the call chain
    "execl->do_execveat_common->bprm_execve->load_elf_binary".

    In do_mmap,it will call mmap_region to create vma node, initialize it and
    insert it to vma maintain structure in mm_struct and i_mmap tree of the
    mapping file, then increase map_count to record the number of vma nodes
    used.  The hot osq_lock is to protect operations on file's i_mmap tree.
    For the mm_struct member change like vma insertion and map_count update,
    they do not affect i_mmap tree.  Move those operations out of the lock's
    critical section, to reduce hold time on the lock.

    With this change, on Intel Sapphire Rapids 112C/224T platform, based on
    v6.0-rc6, the 160 parallel score improves by 12%.  The patch has no
    obvious performance gain on v6.5-rc1 due to regression of this benchmark
    from this commit f1a7941243c102a44e8847e3b94ff4ff3ec56f25 (mm: convert
    mm's rss stats into percpu_counter).  Related discussion and conclusion
    can be referred at the mail thread initiated by 0day as below: Link:
    https://lore.kernel.org/linux-mm/a4aa2e13-7187-600b-c628-7e8fb108def0@intel.com/

    Link: https://lkml.kernel.org/r/20230712145739.604215-1-yu.ma@intel.com
    Signed-off-by: Yu Ma <yu.ma@intel.com>
    Reviewed-by: Tim Chen <tim.c.chen@linux.intel.com>
    Cc: Dan Williams <dan.j.williams@intel.com>
    Cc: Dave Hansen <dave.hansen@intel.com>
    Cc: Kirill A . Shutemov <kirill@shutemov.name>
    Cc: Liam R. Howlett <Liam.Howlett@oracle.com>
    Cc: Shakeel Butt <shakeelb@google.com>
    Cc: Zhu, Lipeng <lipeng.zhu@intel.com>
    Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Signed-off-by: Rafael Aquini <raquini@redhat.com>
This commit is contained in:
Rafael Aquini 2024-09-27 10:43:35 -04:00
parent 5208a88a9c
commit 79f3a0c13d
1 changed files with 1 additions and 7 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

8
mm/mmap.c
View File

@ -419,10 +419,6 @@ static int vma_link(struct mm_struct *mm, struct vm_area_struct *vma)
if (vma->vm_file) {
mapping = vma->vm_file->f_mapping;
i_mmap_lock_write(mapping);
}
if (mapping) {
__vma_link_file(vma, mapping);
i_mmap_unlock_write(mapping);
}
@ -2849,12 +2845,10 @@ cannot_expand:
/* Lock the VMA since it is modified after insertion into VMA tree */
vma_start_write(vma);
if (vma->vm_file)
i_mmap_lock_write(vma->vm_file->f_mapping);
vma_iter_store(&vmi, vma);
mm->map_count++;
if (vma->vm_file) {
i_mmap_lock_write(vma->vm_file->f_mapping);
if (vma->vm_flags & VM_SHARED)
mapping_allow_writable(vma->vm_file->f_mapping);