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From: Qian Cai <cai@lca.pw>
To: "Kirill A. Shutemov" <kirill@shutemov.name>,
	Matthew Wilcox <willy@infradead.org>
Cc: Huang Ying <ying.huang@intel.com>, linux-mm@kvack.org
Subject: Re: page cache: Store only head pages in i_pages
Date: Thu, 04 Apr 2019 09:10:10 -0400	[thread overview]
Message-ID: <1554383410.26196.39.camel@lca.pw> (raw)
In-Reply-To: <20190401092716.mxw32y4sl66ywc2o@kshutemo-mobl1>

On Mon, 2019-04-01 at 12:27 +0300, Kirill A. Shutemov wrote:
> What about patch like this? (completely untested)
> 
> diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h
> index f939e004c5d1..e3b9bf843dcb 100644
> --- a/include/linux/pagemap.h
> +++ b/include/linux/pagemap.h
> @@ -335,12 +335,12 @@ static inline struct page *grab_cache_page_nowait(struct
> address_space *mapping,
>  
>  static inline struct page *find_subpage(struct page *page, pgoff_t offset)
>  {
> -	unsigned long index = page_index(page);
> +	unsigned long mask;
>  
>  	VM_BUG_ON_PAGE(PageTail(page), page);
> -	VM_BUG_ON_PAGE(index > offset, page);
> -	VM_BUG_ON_PAGE(index + (1 << compound_order(page)) <= offset, page);
> -	return page - index + offset;
> +
> +	mask = (1UL << compound_order(page)) - 1;
> +	return page + (offset & mask);
>  }
>  
>  struct page *find_get_entry(struct address_space *mapping, pgoff_t offset);

No, this then leads to a panic below by LTP hugemmap05.  Still reverting the
whole "mm: page cache: store only head pages in i_pages" commit fixed the
problem.

# /opt/ltp/testcases/bin/hugemmap05
tst_test.c:1096: INFO: Timeout per run is 0h 05m 00s
hugemmap05.c:235: INFO: original nr_hugepages is 0
hugemmap05.c:248: INFO: original nr_overcommit_hugepages is 0
hugemmap05.c:116: INFO: check /proc/meminfo before allocation.
hugemmap05.c:297: INFO: HugePages_Total is 192.
hugemmap05.c:297: INFO: HugePages_Free is 192.
hugemmap05.c:297: INFO: HugePages_Surp is 64.
hugemmap05.c:297: INFO: HugePages_Rsvd is 192.
hugemmap05.c:272: INFO: First hex is 7070707
hugemmap05.c:151: INFO: check /proc/meminfo.
hugemmap05.c:297: INFO: HugePages_Total is 192.
hugemmap05.c:297: INFO: HugePages_Free is 0.
hugemmap05.c:297: INFO: HugePages_Surp is 64.
hugemmap05.c:297: INFO: HugePages_Rsvd is 0.


[10022.547977] ------------[ cut here ]------------ 
[10022.571941] kernel BUG at fs/hugetlbfs/inode.c:475! 
[10022.598304] invalid opcode: 0000 [#1] SMP DEBUG_PAGEALLOC KASAN PTI 
[10022.626383] CPU: 39 PID: 13074 Comm: hugemmap05 Kdump: loaded Tainted:
G        W         5.1.0-rc3-next-20190403+ #16 
[10022.674421] Hardware name: HP ProLiant XL420 Gen9/ProLiant XL420 Gen9, BIOS
U19 12/27/2015 
[10022.711990] RIP: 0010:remove_inode_hugepages+0x706/0xa60 
[10022.735997] Code: fd ff ff e8 9c a0 99 ff e9 bc fc ff ff 48 c7 c6 40 ae 50 9f
4c 89 f7 e8 c8 3f ca ff 0f 0b 48 c7 c7 80 18 ba 9f e8 2f 63 15 00 <0f> 0b 48 c7
c7 40 18 ba 9f e8 21 63 15 00 48 8b bd 88 fd ff ff e8 
[10022.820547] RSP: 0018:ffff88883ea5f920 EFLAGS: 00010202 
[10022.844039] RAX: 015fffe000002000 RBX: 0000000000000001 RCX:
ffffffff9e2adf5c 
[10022.876130] RDX: 0000000000000001 RSI: 00000000000001df RDI:
ffffea001a0f8048 
[10022.908202] RBP: ffff88883ea5fbf8 R08: fffff9400341f00b R09:
fffff9400341f00a 
[10022.940369] R10: fffff9400341f00a R11: ffffea001a0f8057 R12:
0000000000000001 
[10022.972615] R13: ffff88883ea5fbd0 R14: ffffea001a0f8040 R15:
dffffc0000000000 
[10023.004633] FS:  00007ff5964d7740(0000) GS:ffff888847b80000(0000)
knlGS:0000000000000000 
[10023.040462] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033 
[10023.066242] CR2: 00007ff595800000 CR3: 00000004be5d0006 CR4:
00000000001606a0 
[10023.103426] Call Trace: 
[10023.114997]  ? hugetlbfs_size_to_hpages+0xe0/0xe0 
[10023.136032]  ? fsnotify_grab_connector+0x9f/0x130 
[10023.157131]  ? __lock_acquire.isra.14+0x7d7/0x2130 
[10023.178540]  ? kasan_check_read+0x11/0x20 
[10023.196471]  ? do_raw_spin_unlock+0x59/0x250 
[10023.215893]  hugetlbfs_evict_inode+0x20/0x90 
[10023.235249]  evict+0x2a4/0x5c0 
[10023.249393]  ? do_raw_spin_unlock+0x59/0x250 
[10023.268885]  iput+0x3d9/0x790 
[10023.282210]  do_unlinkat+0x461/0x650 
[10023.298318]  ? __x64_sys_rmdir+0x40/0x40 
[10023.316058]  ? __check_object_size+0x4b4/0x7f1 
[10023.336241]  ? __kasan_kmalloc.constprop.1+0xac/0xc0 
[10023.358681]  ? blkcg_exit_queue+0x1a0/0x1a0 
[10023.377428]  ? getname_flags+0x90/0x400 
[10023.394859]  __x64_sys_unlink+0x3e/0x50 
[10023.411987]  do_syscall_64+0xeb/0xb78 
[10023.428386]  ? syscall_return_slowpath+0x160/0x160 
[10023.449987]  ? __do_page_fault+0x583/0x8d0 
[10023.468333]  ? schedule+0x81/0x180 
[10023.483515]  ? exit_to_usermode_loop+0xab/0x100 
[10023.503763]  entry_SYSCALL_64_after_hwframe+0x44/0xa9 
[10023.526369] RIP: 0033:0x7ff595bbcedb 


  reply	other threads:[~2019-04-04 13:10 UTC|newest]

Thread overview: 21+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <1553285568.26196.24.camel@lca.pw>
2019-03-23  3:38 ` page cache: Store only head pages in i_pages Matthew Wilcox
2019-03-23 23:50   ` Qian Cai
2019-03-24  2:06     ` Matthew Wilcox
2019-03-24  2:52       ` Qian Cai
2019-03-24  3:04         ` Matthew Wilcox
2019-03-24 15:42           ` Qian Cai
2019-03-27 10:48           ` William Kucharski
2019-03-27 11:50             ` Matthew Wilcox
2019-03-29  1:43           ` Qian Cai
2019-03-29 19:59             ` Matthew Wilcox
2019-03-29 21:25               ` Qian Cai
2019-03-30  3:04                 ` Matthew Wilcox
2019-03-30 14:10                   ` Matthew Wilcox
2019-03-31  3:23                     ` Matthew Wilcox
2019-04-01  9:18                       ` Kirill A. Shutemov
2019-04-01  9:27                         ` Kirill A. Shutemov
2019-04-04 13:10                           ` Qian Cai [this message]
2019-04-04 13:45                             ` Kirill A. Shutemov
2019-04-04 21:28                               ` Qian Cai
2019-04-05 13:37                                 ` Kirill A. Shutemov
2019-04-05 13:51                                   ` Matthew Wilcox

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