On Sat, Mar 17, 2018 at 11:11:06PM +0900, Tetsuo Handa wrote:
> Kirill A. Shutemov noticed that calling lock_page[_killable]() from
> reclaim context might cause deadlock. In order to help finding such
> lock_page[_killable]() users (including out of tree users), this patch
> emits warning messages when CONFIG_PROVE_LOCKING is enabled.
>
> [ 81.532721] ------------[ cut here ]------------
> [ 81.534253] lock_page() from reclaim context might deadlock
> [ 81.534264] WARNING: CPU: 3 PID: 56 at mm/filemap.c:3340 __warn_lock_page_from_reclaim_context+0x1e/0x30
> [ 81.539982] Modules linked in: pcspkr sg vmw_vmci shpchp i2c_piix4 sd_mod ata_generic pata_acpi vmwgfx drm_kms_helper syscopyarea sysfillrect mptspi sysimgblt fb_sys_fops ahci ttm libahci e1000 scsi_transport_spi mptscsih drm ata_piix mptbase i2c_core libata serio_raw ipv6
> [ 81.546750] CPU: 3 PID: 56 Comm: kswapd0 Kdump: loaded Not tainted 4.16.0-rc5-next-20180316+ #698
> [ 81.549333] Hardware name: VMware, Inc. VMware Virtual Platform/440BX Desktop Reference Platform, BIOS 6.00 05/19/2017
> [ 81.552256] RIP: 0010:__warn_lock_page_from_reclaim_context+0x1e/0x30
> [ 81.554164] RSP: 0018:ffffc9000085bbf8 EFLAGS: 00010282
> [ 81.555833] RAX: 0000000000000000 RBX: ffffea0004b2b880 RCX: 0000000000000007
> [ 81.558283] RDX: 0000000000000b6d RSI: ffff88013aa0b700 RDI: ffff88013aa0ae80
> [ 81.562130] RBP: 0000000000000000 R08: 0000000000000001 R09: 0000000000000000
> [ 81.564291] R10: 0000000000000040 R11: 0000000000000000 R12: ffff8801357b4958
> [ 81.566551] R13: 0000000000000000 R14: ffffffff82068220 R15: 0000000000000002
> [ 81.568956] FS: 0000000000000000(0000) GS:ffff88013bcc0000(0000) knlGS:0000000000000000
> [ 81.571310] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> [ 81.573193] CR2: 00000000006020bf CR3: 000000000200f005 CR4: 00000000001606e0
> [ 81.575453] Call Trace:
> [ 81.577001] pagecache_get_page+0x22a/0x230
> [ 81.578497] ? iput+0x52/0x2f0
> [ 81.579762] shmem_unused_huge_shrink+0x2e9/0x380
> [ 81.581465] super_cache_scan+0x17a/0x180
> [ 81.582999] shrink_slab+0x218/0x590
> [ 81.584398] shrink_node+0x346/0x350
> [ 81.585777] kswapd+0x322/0x930
> [ 81.587090] kthread+0xf0/0x130
> [ 81.588370] ? mem_cgroup_shrink_node+0x320/0x320
> [ 81.589996] ? kthread_create_on_node+0x60/0x60
> [ 81.591670] ret_from_fork+0x3a/0x50
> [ 81.593716] Code: f0 41 80 8c 24 08 01 00 00 02 eb b3 90 80 3d b8 54 f8 00 00 74 02 f3 c3 48 c7 c7 b0 87 df 81 c6 05 a6 54 f8 00 01 e8 d2 89 ee ff <0f> 0b c3 0f 1f 44 00 00 66 2e 0f 1f 84 00 00 00 00 00 41 55 41
> [ 81.599356] ---[ end trace d9238c3d53557ed5 ]---
>
> Signed-off-by: Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx>
> Cc: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
> Cc: Michal Hocko <mhocko@xxxxxxxx>
> ---
> include/linux/pagemap.h | 12 ++++++++++++
> mm/filemap.c | 8 ++++++++
> 2 files changed, 20 insertions(+)
>
> diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h
> index 34ce3ebf..8e38f4a 100644
> --- a/include/linux/pagemap.h
> +++ b/include/linux/pagemap.h
> @@ -467,6 +467,10 @@ extern int __lock_page_or_retry(struct page *page, struct mm_struct *mm,
> unsigned int flags);
> extern void unlock_page(struct page *page);
>
> +#ifdef CONFIG_PROVE_LOCKING
> +extern void __warn_lock_page_from_reclaim_context(void);
> +#endif
> +
No need in ifdeffery around declarations. They are harmless.
> static inline int trylock_page(struct page *page)
> {
> page = compound_head(page);
> @@ -479,6 +483,10 @@ static inline int trylock_page(struct page *page)
> static inline void lock_page(struct page *page)
> {
> might_sleep();
> +#ifdef CONFIG_PROVE_LOCKING
> + if (unlikely(current->flags & PF_MEMALLOC))
IS_ENABLED(CONFIG_PROVE_LOCKING)
> + __warn_lock_page_from_reclaim_context();
> +#endif
> if (!trylock_page(page))
> __lock_page(page);
> }
> @@ -491,6 +499,10 @@ static inline void lock_page(struct page *page)
> static inline int lock_page_killable(struct page *page)
> {
> might_sleep();
> +#ifdef CONFIG_PROVE_LOCKING
> + if (unlikely(current->flags & PF_MEMALLOC))
Ditto.
> + __warn_lock_page_from_reclaim_context();
> +#endif
> if (!trylock_page(page))
> return __lock_page_killable(page);
> return 0;
> diff --git a/mm/filemap.c b/mm/filemap.c
> index 693f622..de2eb21 100644
> --- a/mm/filemap.c
> +++ b/mm/filemap.c
> @@ -3328,3 +3328,11 @@ int try_to_release_page(struct page *page, gfp_t gfp_mask)
> }
>
> EXPORT_SYMBOL(try_to_release_page);
> +
> +#ifdef CONFIG_PROVE_LOCKING
> +void __warn_lock_page_from_reclaim_context(void)
> +{
> + WARN_ONCE(1, "lock_page() from reclaim context might deadlock");
> +}
> +EXPORT_SYMBOL(__warn_lock_page_from_reclaim_context);
> +#endif
> --
> 1.8.3.1
>
--
Kirill A. Shutemov
