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BUG: KCSAN: data-race in __delete_from_page_cache / shmem_recalc_inode

write to 0xffff8880ac06de10 of 8 bytes by task 12576 on cpu 0:
 page_cache_delete mm/filemap.c:153 [inline]
 __delete_from_page_cache+0x1d8/0x490 mm/filemap.c:238
 __remove_mapping+0x2db/0x530 mm/vmscan.c:925
 shrink_page_list+0xf57/0x2710 mm/vmscan.c:1425
 reclaim_pages+0x52f/0x6f0 mm/vmscan.c:2139
 madvise_cold_or_pageout_pte_range+0xd4d/0x1860 mm/madvise.c:377
 walk_pmd_range mm/pagewalk.c:89 [inline]
 walk_pud_range mm/pagewalk.c:160 [inline]
 walk_p4d_range mm/pagewalk.c:193 [inline]
 walk_pgd_range mm/pagewalk.c:229 [inline]
 __walk_page_range+0xa67/0x15e0 mm/pagewalk.c:331
 walk_page_range+0x148/0x270 mm/pagewalk.c:427
 madvise_pageout_page_range mm/madvise.c:514 [inline]
 madvise_pageout+0x179/0x220 mm/madvise.c:550
 madvise_vma mm/madvise.c:939 [inline]
 do_madvise mm/madvise.c:1121 [inline]
 do_madvise+0x865/0x1230 mm/madvise.c:1047
 __do_sys_madvise mm/madvise.c:1147 [inline]
 __se_sys_madvise mm/madvise.c:1145 [inline]
 __x64_sys_madvise+0x4c/0x60 mm/madvise.c:1145
 do_syscall_64+0xcc/0x3a0 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff8880ac06de10 of 8 bytes by task 12579 on cpu 1:
 shmem_recalc_inode+0x54/0x190 mm/shmem.c:306
 shmem_getpage_gfp+0x552/0x1390 mm/shmem.c:1890
 shmem_fault+0x114/0x470 mm/shmem.c:2067
 __do_fault+0xae/0x1f0 mm/memory.c:3276
 do_read_fault mm/memory.c:3673 [inline]
 do_fault mm/memory.c:3802 [inline]
 handle_pte_fault mm/memory.c:4033 [inline]
 __handle_mm_fault+0x270d/0x2e00 mm/memory.c:4163
 handle_mm_fault+0x21b/0x530 mm/memory.c:4200
 faultin_page mm/gup.c:659 [inline]
 __get_user_pages+0x485/0x1130 mm/gup.c:870
 populate_vma_page_range+0xe6/0x100 mm/gup.c:1181
 __mm_populate+0x168/0x2a0 mm/gup.c:1229
 mm_populate include/linux/mm.h:2343 [inline]
 vm_mmap_pgoff+0x181/0x190 mm/util.c:511
 ksys_mmap_pgoff+0x99/0x420 mm/mmap.c:1597
 __do_sys_mmap arch/x86/kernel/sys_x86_64.c:99 [inline]
 __se_sys_mmap arch/x86/kernel/sys_x86_64.c:90 [inline]
 __x64_sys_mmap+0x2e/0x40 arch/x86/kernel/sys_x86_64.c:90
 do_syscall_64+0xcc/0x3a0 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 12579 Comm: syz-executor.1 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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