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From: Andrew Morton <akpm@linux-foundation.org>
To: akpm@linux-foundation.org, alex.shi@linux.alibaba.com,
	hannes@cmpxchg.org, linmiaohe@huawei.com, linux-mm@kvack.org,
	longman@redhat.com, mhocko@suse.com, mm-commits@vger.kernel.org,
	smuchun@gmail.com, stable@vger.kernel.org,
	torvalds@linux-foundation.org, willy@infradead.org
Subject: [patch 13/18] mm/filemap: add missing mem_cgroup_uncharge() to __add_to_page_cache_locked()
Date: Thu, 04 Feb 2021 18:32:45 -0800	[thread overview]
Message-ID: <20210205023245.2MSWh6RsL%akpm@linux-foundation.org> (raw)
In-Reply-To: <20210204183135.e123f0d6027529f2cf500cf2@linux-foundation.org>

From: Waiman Long <longman@redhat.com>
Subject: mm/filemap: add missing mem_cgroup_uncharge() to __add_to_page_cache_locked()

commit 3fea5a499d57 ("mm: memcontrol: convert page cache to a new
mem_cgroup_charge() API") introduced a bug in __add_to_page_cache_locked()
causing the following splat:

 [ 1570.068330] page dumped because: VM_BUG_ON_PAGE(page_memcg(page))
 [ 1570.068333] pages's memcg:ffff8889a4116000
 [ 1570.068343] ------------[ cut here ]------------
 [ 1570.068346] kernel BUG at mm/memcontrol.c:2924!
 [ 1570.068355] invalid opcode: 0000 [#1] SMP KASAN PTI
 [ 1570.068359] CPU: 35 PID: 12345 Comm: cat Tainted: G S      W I       5.11.0-rc4-debug+ #1
 [ 1570.068363] Hardware name: HP HP Z8 G4 Workstation/81C7, BIOS P60 v01.25 12/06/2017
 [ 1570.068365] RIP: 0010:commit_charge+0xf4/0x130
   :
 [ 1570.068375] RSP: 0018:ffff8881b38d70e8 EFLAGS: 00010286
 [ 1570.068379] RAX: 0000000000000000 RBX: ffffea00260ddd00 RCX: 0000000000000027
 [ 1570.068382] RDX: 0000000000000000 RSI: 0000000000000004 RDI: ffff88907ebe05a8
 [ 1570.068384] RBP: ffffea00260ddd00 R08: ffffed120fd7c0b6 R09: ffffed120fd7c0b6
 [ 1570.068386] R10: ffff88907ebe05ab R11: ffffed120fd7c0b5 R12: ffffea00260ddd38
 [ 1570.068389] R13: ffff8889a4116000 R14: ffff8889a4116000 R15: 0000000000000001
 [ 1570.068391] FS:  00007ff039638680(0000) GS:ffff88907ea00000(0000) knlGS:0000000000000000
 [ 1570.068394] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
 [ 1570.068396] CR2: 00007f36f354cc20 CR3: 00000008a0126006 CR4: 00000000007706e0
 [ 1570.068398] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
 [ 1570.068400] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
 [ 1570.068402] PKRU: 55555554
 [ 1570.068404] Call Trace:
 [ 1570.068407]  mem_cgroup_charge+0x175/0x770
 [ 1570.068413]  __add_to_page_cache_locked+0x712/0xad0
 [ 1570.068439]  add_to_page_cache_lru+0xc5/0x1f0
 [ 1570.068461]  cachefiles_read_or_alloc_pages+0x895/0x2e10 [cachefiles]
 [ 1570.068524]  __fscache_read_or_alloc_pages+0x6c0/0xa00 [fscache]
 [ 1570.068540]  __nfs_readpages_from_fscache+0x16d/0x630 [nfs]
 [ 1570.068585]  nfs_readpages+0x24e/0x540 [nfs]
 [ 1570.068693]  read_pages+0x5b1/0xc40
 [ 1570.068711]  page_cache_ra_unbounded+0x460/0x750
 [ 1570.068729]  generic_file_buffered_read_get_pages+0x290/0x1710
 [ 1570.068756]  generic_file_buffered_read+0x2a9/0xc30
 [ 1570.068832]  nfs_file_read+0x13f/0x230 [nfs]
 [ 1570.068872]  new_sync_read+0x3af/0x610
 [ 1570.068901]  vfs_read+0x339/0x4b0
 [ 1570.068909]  ksys_read+0xf1/0x1c0
 [ 1570.068920]  do_syscall_64+0x33/0x40
 [ 1570.068926]  entry_SYSCALL_64_after_hwframe+0x44/0xa9
 [ 1570.068930] RIP: 0033:0x7ff039135595

Before that commit, there was a try_charge() and commit_charge() in
__add_to_page_cache_locked().  These 2 separated charge functions were
replaced by a single mem_cgroup_charge().  However, it forgot to add a
matching mem_cgroup_uncharge() when the xarray insertion failed with the
page released back to the pool.  Fix this by adding a
mem_cgroup_uncharge() call when insertion error happens.

Link: https://lkml.kernel.org/r/20210125042441.20030-1-longman@redhat.com
Fixes: 3fea5a499d57 ("mm: memcontrol: convert page cache to a new mem_cgroup_charge() API")
Signed-off-by: Waiman Long <longman@redhat.com>
Reviewed-by: Alex Shi <alex.shi@linux.alibaba.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Muchun Song <smuchun@gmail.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/filemap.c |    4 ++++
 1 file changed, 4 insertions(+)

--- a/mm/filemap.c~mm-filemap-adding-missing-mem_cgroup_uncharge-to-__add_to_page_cache_locked
+++ a/mm/filemap.c
@@ -835,6 +835,7 @@ noinline int __add_to_page_cache_locked(
 	XA_STATE(xas, &mapping->i_pages, offset);
 	int huge = PageHuge(page);
 	int error;
+	bool charged = false;
 
 	VM_BUG_ON_PAGE(!PageLocked(page), page);
 	VM_BUG_ON_PAGE(PageSwapBacked(page), page);
@@ -848,6 +849,7 @@ noinline int __add_to_page_cache_locked(
 		error = mem_cgroup_charge(page, current->mm, gfp);
 		if (error)
 			goto error;
+		charged = true;
 	}
 
 	gfp &= GFP_RECLAIM_MASK;
@@ -896,6 +898,8 @@ unlock:
 
 	if (xas_error(&xas)) {
 		error = xas_error(&xas);
+		if (charged)
+			mem_cgroup_uncharge(page);
 		goto error;
 	}
 
_


  parent reply	other threads:[~2021-02-05  2:32 UTC|newest]

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-02-05  2:31 incoming Andrew Morton
2021-02-05  2:32 ` [patch 01/18] mm: hugetlbfs: fix cannot migrate the fallocated HugeTLB page Andrew Morton
2021-02-05  2:32 ` [patch 02/18] mm: hugetlb: fix a race between freeing and dissolving the page Andrew Morton
2021-02-05  2:32 ` [patch 03/18] mm: hugetlb: fix a race between isolating and freeing page Andrew Morton
2021-02-05  2:32 ` [patch 04/18] mm: hugetlb: remove VM_BUG_ON_PAGE from page_huge_active Andrew Morton
2021-02-05  2:32 ` [patch 05/18] mm: migrate: do not migrate HugeTLB page whose refcount is one Andrew Morton
2021-02-05  2:32 ` [patch 06/18] mm, compaction: move high_pfn to the for loop scope Andrew Morton
2021-02-05  2:32 ` [patch 07/18] mm/vmalloc: separate put pages and flush VM flags Andrew Morton
2021-02-05  2:32 ` [patch 08/18] init/gcov: allow CONFIG_CONSTRUCTORS on UML to fix module gcov Andrew Morton
2021-02-05  2:32 ` [patch 09/18] mm: thp: fix MADV_REMOVE deadlock on shmem THP Andrew Morton
2021-02-05  2:32 ` [patch 10/18] memblock: do not start bottom-up allocations with kernel_end Andrew Morton
2021-02-05  2:32 ` [patch 11/18] mailmap: fix name/email for Viresh Kumar Andrew Morton
2021-02-05  2:32 ` [patch 12/18] mailmap: add entries for Manivannan Sadhasivam Andrew Morton
2021-02-05  2:32 ` Andrew Morton [this message]
2021-02-05  2:32 ` [patch 14/18] kasan: add explicit preconditions to kasan_report() Andrew Morton
2021-02-05  2:32 ` [patch 15/18] kasan: make addr_has_metadata() return true for valid addresses Andrew Morton
2021-02-05  2:32 ` [patch 16/18] ubsan: implement __ubsan_handle_alignment_assumption Andrew Morton
2021-02-05  2:33 ` [patch 17/18] mm: hugetlb: fix missing put_page in gather_surplus_pages() Andrew Morton
2021-02-05  2:33 ` [patch 18/18] MAINTAINERS/.mailmap: use my @kernel.org address Andrew Morton

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