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7e934cf5ac
xas_for_each_marked() is using entry == NULL as a termination condition
of the iteration. When xas_for_each_marked() is used protected only by
RCU, this can however race with xas_store(xas, NULL) in the following
way:
TASK1 TASK2
page_cache_delete() find_get_pages_range_tag()
xas_for_each_marked()
xas_find_marked()
off = xas_find_chunk()
xas_store(&xas, NULL)
xas_init_marks(&xas);
...
rcu_assign_pointer(*slot, NULL);
entry = xa_entry(off);
And thus xas_for_each_marked() terminates prematurely possibly leading
to missed entries in the iteration (translating to missing writeback of
some pages or a similar problem).
If we find a NULL entry that has been marked, skip it (unless we're trying
to allocate an entry).
Reported-by: Jan Kara <jack@suse.cz>
CC: stable@vger.kernel.org
Fixes: ef8e5717db ("page cache: Convert delete_batch to XArray")
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
57 lines
1.5 KiB
Makefile
57 lines
1.5 KiB
Makefile
# SPDX-License-Identifier: GPL-2.0
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CFLAGS += -I. -I../../include -g -Og -Wall -D_LGPL_SOURCE -fsanitize=address \
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-fsanitize=undefined
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LDFLAGS += -fsanitize=address -fsanitize=undefined
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LDLIBS+= -lpthread -lurcu
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TARGETS = main idr-test multiorder xarray
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CORE_OFILES := xarray.o radix-tree.o idr.o linux.o test.o find_bit.o bitmap.o
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OFILES = main.o $(CORE_OFILES) regression1.o regression2.o regression3.o \
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regression4.o tag_check.o multiorder.o idr-test.o iteration_check.o \
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iteration_check_2.o benchmark.o
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ifndef SHIFT
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SHIFT=3
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endif
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ifeq ($(BUILD), 32)
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CFLAGS += -m32
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LDFLAGS += -m32
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endif
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targets: generated/map-shift.h $(TARGETS)
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main: $(OFILES)
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idr-test.o: ../../../lib/test_ida.c
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idr-test: idr-test.o $(CORE_OFILES)
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xarray: $(CORE_OFILES)
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multiorder: multiorder.o $(CORE_OFILES)
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clean:
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$(RM) $(TARGETS) *.o radix-tree.c idr.c generated/map-shift.h
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vpath %.c ../../lib
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$(OFILES): Makefile *.h */*.h generated/map-shift.h \
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../../include/linux/*.h \
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../../include/asm/*.h \
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../../../include/linux/xarray.h \
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../../../include/linux/radix-tree.h \
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../../../include/linux/idr.h
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radix-tree.c: ../../../lib/radix-tree.c
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sed -e 's/^static //' -e 's/__always_inline //' -e 's/inline //' < $< > $@
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idr.c: ../../../lib/idr.c
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sed -e 's/^static //' -e 's/__always_inline //' -e 's/inline //' < $< > $@
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xarray.o: ../../../lib/xarray.c ../../../lib/test_xarray.c
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generated/map-shift.h:
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@if ! grep -qws $(SHIFT) generated/map-shift.h; then \
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echo "#define XA_CHUNK_SHIFT $(SHIFT)" > \
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generated/map-shift.h; \
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fi
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