syzbot

==================================================================
BUG: KCSAN: data-race in shmem_add_to_page_cache / shmem_get_folio_gfp

read-write to 0xffff888107b52030 of 8 bytes by task 1101 on cpu 0:
 shmem_add_to_page_cache+0x40a/0x510 mm/shmem.c:742
 shmem_get_folio_gfp+0x923/0x1200 mm/shmem.c:1980
 shmem_fault+0xe6/0x3f0 mm/shmem.c:2165
 __do_fault mm/memory.c:4198 [inline]
 do_shared_fault mm/memory.c:4602 [inline]
 do_fault mm/memory.c:4674 [inline]
 do_pte_missing mm/memory.c:3664 [inline]
 handle_pte_fault mm/memory.c:4939 [inline]
 __handle_mm_fault mm/memory.c:5079 [inline]
 handle_mm_fault+0x131b/0x2c10 mm/memory.c:5233
 faultin_page mm/gup.c:963 [inline]
 __get_user_pages+0x42e/0xd20 mm/gup.c:1262
 faultin_vma_page_range+0x7e/0xa0 mm/gup.c:1711
 madvise_populate mm/madvise.c:936 [inline]
 madvise_vma_behavior mm/madvise.c:1045 [inline]
 madvise_walk_vmas mm/madvise.c:1267 [inline]
 do_madvise+0x97c/0x29b0 mm/madvise.c:1447
 __do_sys_madvise mm/madvise.c:1460 [inline]
 __se_sys_madvise mm/madvise.c:1458 [inline]
 __x64_sys_madvise+0x60/0x70 mm/madvise.c:1458
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

read to 0xffff888107b52030 of 8 bytes by task 1088 on cpu 1:
 shmem_recalc_inode mm/shmem.c:360 [inline]
 shmem_get_folio_gfp+0xe1e/0x1200 mm/shmem.c:1990
 shmem_fault+0xe6/0x3f0 mm/shmem.c:2165
 __do_fault mm/memory.c:4198 [inline]
 do_shared_fault mm/memory.c:4602 [inline]
 do_fault mm/memory.c:4674 [inline]
 do_pte_missing mm/memory.c:3664 [inline]
 handle_pte_fault mm/memory.c:4939 [inline]
 __handle_mm_fault mm/memory.c:5079 [inline]
 handle_mm_fault+0x131b/0x2c10 mm/memory.c:5233
 faultin_page mm/gup.c:963 [inline]
 __get_user_pages+0x42e/0xd20 mm/gup.c:1262
 faultin_vma_page_range+0x7e/0xa0 mm/gup.c:1711
 madvise_populate mm/madvise.c:936 [inline]
 madvise_vma_behavior mm/madvise.c:1045 [inline]
 madvise_walk_vmas mm/madvise.c:1267 [inline]
 do_madvise+0x97c/0x29b0 mm/madvise.c:1447
 __do_sys_madvise mm/madvise.c:1460 [inline]
 __se_sys_madvise mm/madvise.c:1458 [inline]
 __x64_sys_madvise+0x60/0x70 mm/madvise.c:1458
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

value changed: 0x0000000000000279 -> 0x000000000000027a

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 1088 Comm: syz-executor.1 Not tainted 6.5.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/26/2023
==================================================================