From: Qian Cai <cai@redhat.com>
To: "Matthew Wilcox (Oracle)" <willy@infradead.org>, linux-mm@kvack.org
Cc: intel-gfx@lists.freedesktop.org,
Huang Ying <ying.huang@intel.com>,
Hugh Dickins <hughd@google.com>,
linux-kernel@vger.kernel.org,
Chris Wilson <chris@chris-wilson.co.uk>,
William Kucharski <william.kucharski@oracle.com>,
Johannes Weiner <hannes@cmpxchg.org>,
cgroups@vger.kernel.org,
Andrew Morton <akpm@linux-foundation.org>,
Alexey Dobriyan <adobriyan@gmail.com>,
Matthew Auld <matthew.auld@intel.com>
Subject: Re: [PATCH v2 3/8] mm: Optimise madvise WILLNEED
Date: Mon, 14 Sep 2020 12:17:07 -0400 [thread overview]
Message-ID: <c48c5eaa09d1ea5b78b12b545c034d1e937c49ba.camel@redhat.com> (raw)
In-Reply-To: <20200910183318.20139-4-willy@infradead.org>
On Thu, 2020-09-10 at 19:33 +0100, Matthew Wilcox (Oracle) wrote:
> Instead of calling find_get_entry() for every page index, use an XArray
> iterator to skip over NULL entries, and avoid calling get_page(),
> because we only want the swap entries.
>
> Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
> Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Reverting the "Return head pages from find_*_entry" patchset [1] up to this
patch fixed the issue that LTP madvise06 test [2] would trigger endless soft-
lockups below. It does not help after applied patches fixed other separate
issues in the patchset [3][4].
[1] https://lore.kernel.org/intel-gfx/20200910183318.20139-1-willy@infradead.org/
[2] https://github.com/linux-test-project/ltp/blob/master/testcases/kernel/syscalls/madvise/madvise06.c
[3] https://lore.kernel.org/intel-gfx/20200914112738.GM6583@casper.infradead.org/
[4] https://lore.kernel.org/lkml/20200914115559.GN6583@casper.infradead.org/
[ 2653.179563][ C4] CPU: 4 PID: 23320 Comm: madvise06 Not tainted 5.9.0-rc5-next-20200914+ #2
[ 2653.220176][ C4] Hardware name: HP ProLiant BL660c Gen9, BIOS I38 10/17/2018
[ 2653.254908][ C4] RIP: 0010:lock_acquire+0x211/0x8e0
[ 2653.278534][ C4] Code: 83 c0 03 38 d0 7c 08 84 d2 0f 85 3a 05 00 00 8b 85 04 08 00 00 83 e8 01 89 85 04 08 00 00 66 85 c0 0f 85 9a 04 00 00 41 52 9d <48> b8 00 00 00 00 00 fc ff df 48 01 c3 c7 03 00 00 00 00 c7 43 08
[ 2653.369929][ C4] RSP: 0018:ffffc9000e1bf9f0 EFLAGS: 00000246
[ 2653.399398][ C4] RAX: 0000000000000000 RBX: 1ffff92001c37f41 RCX: 1ffff92001c37f27
[ 2653.437720][ C4] RDX: 0000000000000000 RSI: 0000000029956a3e RDI: ffff889042f40844
[ 2653.475829][ C4] RBP: ffff889042f40040 R08: fffffbfff5083905 R09: fffffbfff5083905
[ 2653.511611][ C4] R10: 0000000000000246 R11: fffffbfff5083904 R12: ffffffffa74ce320
[ 2653.547396][ C4] R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
[ 2653.582938][ C4] FS: 00007f1fc85e4600(0000) GS:ffff88881e100000(0000) knlGS:0000000000000000
[ 2653.622910][ C4] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 2653.652310][ C4] CR2: 0000000000620050 CR3: 000000054d438002 CR4: 00000000001706e0
[ 2653.688228][ C4] Call Trace:
[ 2653.702537][ C4] ? rcu_read_unlock+0x40/0x40
[ 2653.723647][ C4] ? find_held_lock+0x33/0x1c0
[ 2653.744708][ C4] ? __read_swap_cache_async+0x18f/0x870
[ 2653.770547][ C4] get_swap_device+0xf5/0x280
rcu_read_lock at include/linux/rcupdate.h:642
(inlined by) get_swap_device at mm/swapfile.c:1303
[ 2653.791303][ C4] ? get_swap_device+0xce/0x280
[ 2653.812693][ C4] ? swap_page_trans_huge_swapped+0x2a0/0x2a0
[ 2653.839963][ C4] __read_swap_cache_async+0x10c/0x870
__read_swap_cache_async at mm/swap_state.c:469
[ 2653.864243][ C4] ? rcu_read_lock_sched_held+0x9c/0xd0
[ 2653.890657][ C4] ? find_get_incore_page+0x220/0x220
[ 2653.916978][ C4] ? rcu_read_lock_held+0x9c/0xb0
[ 2653.940235][ C4] ? find_held_lock+0x33/0x1c0
[ 2653.961325][ C4] ? do_madvise.part.30+0xd11/0x1b70
[ 2653.984922][ C4] ? lock_downgrade+0x730/0x730
[ 2654.006502][ C4] read_swap_cache_async+0x60/0xb0
read_swap_cache_async at mm/swap_state.c:564
[ 2654.029694][ C4] ? __read_swap_cache_async+0x870/0x870
[ 2654.055486][ C4] ? xas_find+0x410/0x6c0
[ 2654.074663][ C4] do_madvise.part.30+0xd47/0x1b70
force_shm_swapin_readahead at mm/madvise.c:243
(inlined by) madvise_willneed at mm/madvise.c:277
(inlined by) madvise_vma at mm/madvise.c:939
(inlined by) do_madvise at mm/madvise.c:1142
[ 2654.097959][ C4] ? find_held_lock+0x33/0x1c0
[ 2654.119031][ C4] ? swapin_walk_pmd_entry+0x430/0x430
[ 2654.143518][ C4] ? down_read_nested+0x420/0x420
[ 2654.165748][ C4] ? rcu_read_lock_sched_held+0x9c/0xd0
[ 2654.190523][ C4] ? __x64_sys_madvise+0xa1/0x110
[ 2654.212973][ C4] __x64_sys_madvise+0xa1/0x110
[ 2654.233976][ C4] ? syscall_enter_from_user_mode+0x1c/0x50
[ 2654.260983][ C4] do_syscall_64+0x33/0x40
[ 2654.281132][ C4] entry_SYSCALL_64_after_hwframe+0x44/0xa9
[ 2654.307623][ C4] RIP: 0033:0x7f1fc80fca6b
[ 2654.327125][ C4] Code: 64 89 02 b8 ff ff ff ff c3 48 8b 15 17 54 2c 00 f7 d8 64 89 02 b8 ff ff ff ff eb bc 0f 1f 00 f3 0f 1e fa b8 1c 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d ed 53 2c 00 f7 d8 64 89 01 48
[ 2654.420246][ C4] RSP: 002b:00007fff53609998 EFLAGS: 00000202 ORIG_RAX: 000000000000001c
[ 2654.458926][ C4] RAX: ffffffffffffffda RBX: 00007f1fc85e4580 RCX: 00007f1fc80fca6b
[ 2654.494295][ C4] RDX: 0000000000000003 RSI: 0000000019000000 RDI: 00007f1faf006000
[ 2654.530104][ C4] RBP: 00007f1faf006000 R08: 0000000000000000 R09: 00007fff53609284
[ 2654.566057][ C4] R10: 0000000000000003 R11: 0000000000000202 R12: 0000000000000000
[ 2654.601697][ C4] R13: 0000000000000001 R14: 0000000000000000 R15: 0000000000000000
...
[ 2846.587644][ T353] Showing all locks held in the system:
[ 2846.622367][ T353] 1 lock held by khungtaskd/353:
[ 2846.644378][ T353] #0: ffffffffa74ce320 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire.constprop.51+0x0/0x30
[ 2846.695738][ T353] 1 lock held by khugepaged/361:
[ 2846.718056][ T353] #0: ffffffffa75418e8 (lock#4){+.+.}-{3:3}, at: lru_add_drain_all+0x55/0x5f0
[ 2846.758184][ T353] 1 lock held by madvise06/23320:
[ 2846.780486][ T353]
[ 2846.790445][ T353] =============================================
> ---
> mm/madvise.c | 21 ++++++++++++---------
> 1 file changed, 12 insertions(+), 9 deletions(-)
>
> diff --git a/mm/madvise.c b/mm/madvise.c
> index dd1d43cf026d..96189acd6969 100644
> --- a/mm/madvise.c
> +++ b/mm/madvise.c
> @@ -224,25 +224,28 @@ static void force_shm_swapin_readahead(struct
> vm_area_struct *vma,
> unsigned long start, unsigned long end,
> struct address_space *mapping)
> {
> - pgoff_t index;
> + XA_STATE(xas, &mapping->i_pages, linear_page_index(vma, start));
> + pgoff_t end_index = end / PAGE_SIZE;
> struct page *page;
> - swp_entry_t swap;
>
> - for (; start < end; start += PAGE_SIZE) {
> - index = ((start - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff;
> + rcu_read_lock();
> + xas_for_each(&xas, page, end_index) {
> + swp_entry_t swap;
>
> - page = find_get_entry(mapping, index);
> - if (!xa_is_value(page)) {
> - if (page)
> - put_page(page);
> + if (!xa_is_value(page))
> continue;
> - }
> + rcu_read_unlock();
> +
> swap = radix_to_swp_entry(page);
> page = read_swap_cache_async(swap, GFP_HIGHUSER_MOVABLE,
> NULL, 0, false);
> if (page)
> put_page(page);
> +
> + rcu_read_lock();
> + xas_reset(&xas);
> }
> + rcu_read_unlock();
>
> lru_add_drain(); /* Push any new pages onto the LRU now */
> }
next prev parent reply other threads:[~2020-09-14 16:17 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-10 18:33 [PATCH v2 0/8] Return head pages from find_*_entry Matthew Wilcox (Oracle)
2020-09-10 18:33 ` [PATCH v2 1/8] mm: Factor find_get_incore_page out of mincore_page Matthew Wilcox (Oracle)
2020-09-10 18:33 ` [PATCH v2 2/8] mm: Use find_get_incore_page in memcontrol Matthew Wilcox (Oracle)
2020-09-10 18:33 ` [PATCH v2 3/8] mm: Optimise madvise WILLNEED Matthew Wilcox (Oracle)
2020-09-14 16:17 ` Qian Cai [this message]
2020-09-14 16:47 ` Qian Cai
2020-09-14 16:50 ` Matthew Wilcox
2020-09-14 19:44 ` Qian Cai
2020-09-10 18:33 ` [PATCH v2 4/8] proc: Optimise smaps for shmem entries Matthew Wilcox (Oracle)
2020-09-10 18:33 ` [PATCH v2 5/8] i915: Use find_lock_page instead of find_lock_entry Matthew Wilcox (Oracle)
2020-09-10 18:33 ` [PATCH v2 6/8] mm: Convert find_get_entry to return the head page Matthew Wilcox (Oracle)
2020-09-14 8:55 ` [mm] 2037ab69a5: BUG:KASAN:null-ptr-deref_in_t kernel test robot
2020-09-14 11:27 ` Matthew Wilcox
2020-09-10 18:33 ` [PATCH v2 7/8] mm/shmem: Return head page from find_lock_entry Matthew Wilcox (Oracle)
2020-09-12 3:20 ` Matthew Wilcox
2020-09-10 18:33 ` [PATCH v2 8/8] mm: Add find_lock_head Matthew Wilcox (Oracle)
2020-09-15 8:10 ` [PATCH v2 0/8] Return head pages from find_*_entry Hugh Dickins
2020-09-15 12:53 ` Naresh Kamboju
2020-09-15 13:08 ` Matthew Wilcox
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