Re: [LTP] [PATCH] mm: as the same logic with queue_pages_range

Re: [LTP] [PATCH] mm: as the same logic with queue_pages_range

[kernel test robot]

Hello,

kernel test robot noticed "ltp.vma02.fail" on:

commit: 8dfdaf99160833af1a0a4ffef60c94627c77025b ("[PATCH] mm: as the same logic with queue_pages_range")
url: https://github.com/intel-lab-lkp/linux/commits/Edward-AD/mm-as-the-same-logic-with-queue_pages_range/20230906-142110
base: https://git.kernel.org/cgit/linux/kernel/git/akpm/mm.git mm-everything
patch link: https://lore.kernel.org/all/20230906061902.591996-1-eadavis@sina.com/
patch subject: [PATCH] mm: as the same logic with queue_pages_range

in testcase: ltp
version: ltp-x86_64-14c1f76-1_20230715
with following parameters:

	disk: 1HDD
	test: mm-00/vma02



compiler: gcc-12
test machine: 8 threads 1 sockets Intel(R) Core(TM) i7-7700 CPU @ 3.60GHz (Kaby Lake) with 32G memory

(please refer to attached dmesg/kmsg for entire log/backtrace)




If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <oliver.sang@intel.com>
| Closes: https://lore.kernel.org/oe-lkp/202309121302.8864096c-oliver.sang@intel.com



Running tests.......
<<<test_start>>>
tag=vma02 stime=1694438526
cmdline="vma02"
contacts=""
analysis=exit
<<<test_output>>>
vma02       0  TINFO  :  pid = 3639 addr = 0x7f5202dd6000
vma02       0  TINFO  :  start = 0x7f5202dd6000, end = 0x7f5202dd7000
vma02       0  TINFO  :  start = 0x7f5202dd7000, end = 0x7f5202dd8000
vma02       0  TINFO  :  start = 0x7f5202dd8000, end = 0x7f5202dd9000
vma02       1  TFAIL  :  vma02.c:144: >1 unmerged VMAs.
incrementing stop
<<<execution_status>>>
initiation_status="ok"
duration=0 termination_type=exited termination_id=1 corefile=no
cutime=0 cstime=7
<<<test_end>>>
INFO: ltp-pan reported some tests FAIL
LTP Version: 20230516-75-g2e582e743

       ###############################################################

            Done executing testcases.
            LTP Version:  20230516-75-g2e582e743
       ###############################################################




The kernel config and materials to reproduce are available at:
https://download.01.org/0day-ci/archive/20230912/202309121302.8864096c-oliver.sang@intel.com



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Re: [LTP] [PATCH] mm: as the same logic with queue_pages_range

[Cyril Hrubis]

Hi!
> Running tests.......
> <<<test_start>>>
> tag=vma02 stime=1694438526
> cmdline="vma02"
> contacts=""
> analysis=exit
> <<<test_output>>>
> vma02       0  TINFO  :  pid = 3639 addr = 0x7f5202dd6000
> vma02       0  TINFO  :  start = 0x7f5202dd6000, end = 0x7f5202dd7000
> vma02       0  TINFO  :  start = 0x7f5202dd7000, end = 0x7f5202dd8000
> vma02       0  TINFO  :  start = 0x7f5202dd8000, end = 0x7f5202dd9000
> vma02       1  TFAIL  :  vma02.c:144: >1 unmerged VMAs.
> incrementing stop

So the test is reproducer for:

commit 9d8cebd4bcd7c3878462fdfda34bbcdeb4df7ef4
Author: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Date:   Fri Mar 5 13:41:57 2010 -0800

    mm: fix mbind vma merge problem

    Strangely, current mbind() doesn't merge vma with neighbor vma although it's possible.
    Unfortunately, many vma can reduce performance...


And what the test does is:

- map 3 continous pages
- popluate
- mbind() first page
- mbind() all three pages
- checks that there is only single VMA for the pages after second
  mbind()

-- 
Cyril Hrubis
chrubis@suse.cz

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[LTP] [PATCH] mm: extpand queue_pages_range() to find and lock the vma range

[Edward AD]

Using for_each_vma_range to find vmas, and not only inside locking, but also 
outside locking to ensure that vma_start_write are performed.

Reported-and-tested-by: syzbot+b591856e0f0139f83023@syzkaller.appspotmail.com
Signed-off-by: Edward AD <eadavis@sina.com>
---
 mm/pagewalk.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/mm/pagewalk.c b/mm/pagewalk.c
index b7d7e4fcfad7..b31d59a27f57 100644
--- a/mm/pagewalk.c
+++ b/mm/pagewalk.c
@@ -479,6 +479,7 @@ int walk_page_range(struct mm_struct *mm, unsigned long start,
 		.mm		= mm,
 		.private	= private,
 	};
+	struct vma_iterator vmi;
 
 	if (start >= end)
 		return -EINVAL;
@@ -488,8 +489,9 @@ int walk_page_range(struct mm_struct *mm, unsigned long start,
 
 	process_mm_walk_lock(walk.mm, ops->walk_lock);
 
-	vma = find_vma(walk.mm, start);
-	do {
+	vma_iter_init(&vmi, walk.mm, start);
+	for_each_vma_range(vmi, vma, end) {
+		process_vma_walk_lock(vma, ops->walk_lock);
 		if (!vma) { /* after the last vma */
 			walk.vma = NULL;
 			next = end;
@@ -501,10 +503,8 @@ int walk_page_range(struct mm_struct *mm, unsigned long start,
 			if (ops->pte_hole)
 				err = ops->pte_hole(start, next, -1, &walk);
 		} else { /* inside vma */
-			process_vma_walk_lock(vma, ops->walk_lock);
 			walk.vma = vma;
 			next = min(end, vma->vm_end);
-			vma = find_vma(mm, vma->vm_end);
 
 			err = walk_page_test(start, next, &walk);
 			if (err > 0) {
@@ -522,7 +522,7 @@ int walk_page_range(struct mm_struct *mm, unsigned long start,
 		}
 		if (err)
 			break;
-	} while (start = next, start < end);
+	};
 	return err;
 }
 
-- 
2.25.1


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