linux-kernel - [PATCH -next] arm64/mm: fix a bogus GFP flag in pgd

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Date:   Tue,  4 Jun 2019 10:00:36 -0400
From:   Qian Cai <cai@....pw>
To:     akpm@...ux-foundation.org
Cc:     rppt@...ux.ibm.com, will.deacon@....com, catalin.marinas@....com,
        linux-arm-kernel@...ts.infradead.org, hannes@...xchg.org,
        mhocko@...nel.org, vdavydov.dev@...il.com, cgroups@...r.kernel.org,
        linux-mm@...ck.org, linux-kernel@...r.kernel.org,
        Qian Cai <cai@....pw>
Subject: [PATCH -next] arm64/mm: fix a bogus GFP flag in pgd_alloc()

The commit "arm64: switch to generic version of pte allocation"
introduced endless failures during boot like,

kobject_add_internal failed for pgd_cache(285:chronyd.service) (error:
-2 parent: cgroup)

It turns out __GFP_ACCOUNT is passed to kernel page table allocations
and then later memcg finds out those don't belong to any cgroup.

backtrace:
  kobject_add_internal
  kobject_init_and_add
  sysfs_slab_add+0x1a8
  __kmem_cache_create
  create_cache
  memcg_create_kmem_cache
  memcg_kmem_cache_create_func
  process_one_work
  worker_thread
  kthread

Signed-off-by: Qian Cai <cai@....pw>
---
 arch/arm64/mm/pgd.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/arm64/mm/pgd.c b/arch/arm64/mm/pgd.c
index 769516cb6677..53c48f5c8765 100644
--- a/arch/arm64/mm/pgd.c
+++ b/arch/arm64/mm/pgd.c
@@ -38,7 +38,7 @@ pgd_t *pgd_alloc(struct mm_struct *mm)
 	if (PGD_SIZE == PAGE_SIZE)
 		return (pgd_t *)__get_free_page(gfp);
 	else
-		return kmem_cache_alloc(pgd_cache, gfp);
+		return kmem_cache_alloc(pgd_cache, GFP_PGTABLE_KERNEL);
 }
 
 void pgd_free(struct mm_struct *mm, pgd_t *pgd)
-- 
1.8.3.1