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mm: memcontrol: drop @compound parameter from memcg charging API

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The memcg charging API carries a boolean @compound parameter that tells
whether the page we're dealing with is a hugepage.
mem_cgroup_commit_charge() has another boolean @lrucare that indicates
whether the page needs LRU locking or not while charging.  The majority of
callsites know those parameters at compile time, which results in a lot of
naked "false, false" argument lists.  This makes for cryptic code and is a
breeding ground for subtle mistakes.

Thankfully, the huge page state can be inferred from the page itself and
doesn't need to be passed along.  This is safe because charging completes
before the page is published and somebody may split it.

Simplify the callsites by removing @compound, and let memcg infer the
state by using hpage_nr_pages() unconditionally.  That function does
PageTransHuge() to identify huge pages, which also helpfully asserts that
nobody passes in tail pages by accident.

The following patches will introduce a new charging API, best not to carry
over unnecessary weight.

Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Alex Shi <alex.shi@linux.alibaba.com>
Reviewed-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: "Kirill A. Shutemov" <kirill@shutemov.name>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Roman Gushchin <guro@fb.com>
Cc: Balbir Singh <bsingharora@gmail.com>
Link: http://lkml.kernel.org/r/20200508183105.225460-4-hannes@cmpxchg.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Johannes Weiner
2020-06-03 16:01:31 -07:00
committed by Linus Torvalds
parent abb242f571
commit 3fba69a56e
11 changed files with 77 additions and 98 deletions
Download Patch File Download Diff File Expand all files Collapse all files

8
mm/huge_memory.c
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@@ -594,7 +594,7 @@ static vm_fault_t __do_huge_pmd_anonymous_page(struct vm_fault *vmf,
VM_BUG_ON_PAGE(!PageCompound(page), page);
if (mem_cgroup_try_charge_delay(page, vma->vm_mm, gfp, &memcg, true)) {
if (mem_cgroup_try_charge_delay(page, vma->vm_mm, gfp, &memcg)) {
put_page(page);
count_vm_event(THP_FAULT_FALLBACK);
count_vm_event(THP_FAULT_FALLBACK_CHARGE);
@@ -630,7 +630,7 @@ static vm_fault_t __do_huge_pmd_anonymous_page(struct vm_fault *vmf,
vm_fault_t ret2;
spin_unlock(vmf->ptl);
mem_cgroup_cancel_charge(page, memcg, true);
mem_cgroup_cancel_charge(page, memcg);
put_page(page);
pte_free(vma->vm_mm, pgtable);
ret2 = handle_userfault(vmf, VM_UFFD_MISSING);
@@ -641,7 +641,7 @@ static vm_fault_t __do_huge_pmd_anonymous_page(struct vm_fault *vmf,
entry = mk_huge_pmd(page, vma->vm_page_prot);
entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
page_add_new_anon_rmap(page, vma, haddr, true);
mem_cgroup_commit_charge(page, memcg, false, true);
mem_cgroup_commit_charge(page, memcg, false);
lru_cache_add_active_or_unevictable(page, vma);
pgtable_trans_huge_deposit(vma->vm_mm, vmf->pmd, pgtable);
set_pmd_at(vma->vm_mm, haddr, vmf->pmd, entry);
@@ -658,7 +658,7 @@ unlock_release:
release:
if (pgtable)
pte_free(vma->vm_mm, pgtable);
mem_cgroup_cancel_charge(page, memcg, true);
mem_cgroup_cancel_charge(page, memcg);
put_page(page);
return ret;