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authorMatthew Wilcox (Oracle) <willy@infradead.org>2020-10-13 16:56:04 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2020-10-13 18:38:33 -0700
commite320d3012d25b1fb5f3df4edb7bd44a1c362ec10 (patch)
tree045231cbb1f31c38cbb22189a08d284398fc09ae /lib/Makefile
parenta9b576f7253e22528584f5aeb46edf0b6b007992 (diff)
downloadlinux-e320d3012d25b1fb5f3df4edb7bd44a1c362ec10.tar.bz2
mm/page_alloc.c: fix freeing non-compound pages
Here is a very rare race which leaks memory: Page P0 is allocated to the page cache. Page P1 is free. Thread A Thread B Thread C find_get_entry(): xas_load() returns P0 Removes P0 from page cache P0 finds its buddy P1 alloc_pages(GFP_KERNEL, 1) returns P0 P0 has refcount 1 page_cache_get_speculative(P0) P0 has refcount 2 __free_pages(P0) P0 has refcount 1 put_page(P0) P1 is not freed Fix this by freeing all the pages in __free_pages() that won't be freed by the call to put_page(). It's usually not a good idea to split a page, but this is a very unlikely scenario. Fixes: e286781d5f2e ("mm: speculative page references") Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Acked-by: Mike Rapoport <rppt@linux.ibm.com> Cc: Nick Piggin <npiggin@gmail.com> Cc: Hugh Dickins <hughd@google.com> Cc: Peter Zijlstra <peterz@infradead.org> Link: https://lkml.kernel.org/r/20200926213919.26642-1-willy@infradead.org Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'lib/Makefile')
-rw-r--r--lib/Makefile1
1 files changed, 1 insertions, 0 deletions
diff --git a/lib/Makefile b/lib/Makefile
index d4af75136c54..49a2a9e36224 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -101,6 +101,7 @@ obj-$(CONFIG_TEST_BLACKHOLE_DEV) += test_blackhole_dev.o
obj-$(CONFIG_TEST_MEMINIT) += test_meminit.o
obj-$(CONFIG_TEST_LOCKUP) += test_lockup.o
obj-$(CONFIG_TEST_HMM) += test_hmm.o
+obj-$(CONFIG_TEST_FREE_PAGES) += test_free_pages.o
#
# CFLAGS for compiling floating point code inside the kernel. x86/Makefile turns