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BUG: KCSAN: data-race in __es_shrink / __es_shrink

write to 0xffff88821800c478 of 8 bytes by task 8728 on cpu 0:
 __es_shrink+0x373/0x620 fs/ext4/extents_status.c:1517
 ext4_es_scan+0x1cc/0x2d0 fs/ext4/extents_status.c:1559
 do_shrink_slab+0x2a9/0x5b0 mm/vmscan.c:512
 shrink_slab mm/vmscan.c:673 [inline]
 shrink_slab+0x153/0x540 mm/vmscan.c:646
 shrink_node_memcgs mm/vmscan.c:2673 [inline]
 shrink_node+0x354/0x1000 mm/vmscan.c:2777
 shrink_zones mm/vmscan.c:2980 [inline]
 do_try_to_free_pages+0x230/0xb30 mm/vmscan.c:3033
 try_to_free_pages+0x1e6/0x470 mm/vmscan.c:3272
 __perform_reclaim mm/page_alloc.c:4113 [inline]
 __alloc_pages_direct_reclaim mm/page_alloc.c:4134 [inline]
 __alloc_pages_slowpath+0x3cc/0xda0 mm/page_alloc.c:4537
 __alloc_pages_nodemask+0x2c5/0x310 mm/page_alloc.c:4751
 alloc_pages_vma+0xc0/0x390 mm/mempolicy.c:2174
 alloc_zeroed_user_highpage_movable include/linux/highmem.h:208 [inline]
 do_anonymous_page mm/memory.c:3186 [inline]
 handle_pte_fault mm/memory.c:4031 [inline]
 __handle_mm_fault+0x18bb/0x2cf0 mm/memory.c:4163
 handle_mm_fault+0x21c/0x540 mm/memory.c:4200
 do_user_addr_fault arch/x86/mm/fault.c:1442 [inline]
 do_page_fault+0x4a4/0xa52 arch/x86/mm/fault.c:1517
 page_fault+0x34/0x40 arch/x86/entry/entry_64.S:1203

read to 0xffff88821800c478 of 8 bytes by task 8758 on cpu 1:
 __es_shrink+0x33b/0x620 fs/ext4/extents_status.c:1515
 ext4_es_scan+0x1cc/0x2d0 fs/ext4/extents_status.c:1559
 do_shrink_slab+0x2a9/0x5b0 mm/vmscan.c:512
 shrink_slab mm/vmscan.c:673 [inline]
 shrink_slab+0x153/0x540 mm/vmscan.c:646
 shrink_node_memcgs mm/vmscan.c:2673 [inline]
 shrink_node+0x354/0x1000 mm/vmscan.c:2777
 shrink_zones mm/vmscan.c:2980 [inline]
 do_try_to_free_pages+0x230/0xb30 mm/vmscan.c:3033
 try_to_free_pages+0x1e6/0x470 mm/vmscan.c:3272
 __perform_reclaim mm/page_alloc.c:4113 [inline]
 __alloc_pages_direct_reclaim mm/page_alloc.c:4134 [inline]
 __alloc_pages_slowpath+0x3cc/0xda0 mm/page_alloc.c:4537
 __alloc_pages_nodemask+0x2c5/0x310 mm/page_alloc.c:4751
 alloc_pages_vma+0xc0/0x390 mm/mempolicy.c:2174
 alloc_zeroed_user_highpage_movable include/linux/highmem.h:208 [inline]
 do_anonymous_page mm/memory.c:3186 [inline]
 handle_pte_fault mm/memory.c:4031 [inline]
 __handle_mm_fault+0x18bb/0x2cf0 mm/memory.c:4163
 handle_mm_fault+0x21c/0x540 mm/memory.c:4200
 do_user_addr_fault arch/x86/mm/fault.c:1442 [inline]
 do_page_fault+0x4a4/0xa52 arch/x86/mm/fault.c:1517
 page_fault+0x34/0x40 arch/x86/entry/entry_64.S:1203

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 8758 Comm: blkid Not tainted 5.6.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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