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| author | Anders Roxell <anders.roxell@linaro.org> | 2018-12-28 09:33:31 +0100 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2018-12-28 21:11:46 +0100 |
| commit | 368686a95e55fd66b88542b5b23d802a4886b1aa (patch) | |
| tree | ee75130c8e26ce68889b2df895a0f1330e51e626 /mm | |
| parent | mm/mmu_notifier.c: remove mmu_notifier_synchronize() (diff) | |
| download | linux-368686a95e55fd66b88542b5b23d802a4886b1aa.tar.xz linux-368686a95e55fd66b88542b5b23d802a4886b1aa.zip | |
writeback: don't decrement wb->refcnt if !wb->bdi
This happened while running in qemu-system-aarch64, the AMBA PL011 UART
driver when enabling CONFIG_DEBUG_TEST_DRIVER_REMOVE.
arch_initcall(pl011_init) came before subsys_initcall(default_bdi_init),
devtmpfs' handle_remove() crashes because the reference count is a NULL
pointer only because wb->bdi hasn't been initialized yet.
Rework so that wb_put have an extra check if wb->bdi before decrement
wb->refcnt and also add a WARN_ON_ONCE to get a warning if it happens
again in other drivers.
Link: http://lkml.kernel.org/r/20181030113545.30999-2-anders.roxell@linaro.org
Fixes: 52ebea749aae ("writeback: make backing_dev_info host cgroup-specific bdi_writebacks")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Anders Roxell <anders.roxell@linaro.org>
Co-developed-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm')
0 files changed, 0 insertions, 0 deletions