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lib/test_hmm.c: handle src_pfns and dst_pfns allocation failure

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The kcalloc() in dmirror_device_evict_chunk() will return null if the
physical memory has run out.  As a result, if src_pfns or dst_pfns is
dereferenced, the null pointer dereference bug will happen.

Moreover, the device is going away.  If the kcalloc() fails, the pages
mapping a chunk could not be evicted.  So add a __GFP_NOFAIL flag in
kcalloc().

Finally, as there is no need to have physically contiguous memory, Switch
kcalloc() to kvcalloc() in order to avoid failing allocations.

Link: https://lkml.kernel.org/r/20240312005905.9939-1-duoming@zju.edu.cn
Fixes: b2ef9f5a5c ("mm/hmm/test: add selftest driver for HMM")
Signed-off-by: Duoming Zhou <duoming@zju.edu.cn>
Cc: Jérôme Glisse <jglisse@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Duoming Zhou 2024-03-12 08:59:05 +08:00 committed by Andrew Morton
parent 4196b48ddd
commit c2af060d1c
1 changed files with 4 additions and 4 deletions
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8
lib/test_hmm.c
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@ -1226,8 +1226,8 @@ static void dmirror_device_evict_chunk(struct dmirror_chunk *chunk)
unsigned long *src_pfns;
unsigned long *dst_pfns;
src_pfns = kcalloc(npages, sizeof(*src_pfns), GFP_KERNEL);
dst_pfns = kcalloc(npages, sizeof(*dst_pfns), GFP_KERNEL);
src_pfns = kvcalloc(npages, sizeof(*src_pfns), GFP_KERNEL | __GFP_NOFAIL);
dst_pfns = kvcalloc(npages, sizeof(*dst_pfns), GFP_KERNEL | __GFP_NOFAIL);
migrate_device_range(src_pfns, start_pfn, npages);
for (i = 0; i < npages; i++) {
@ -1250,8 +1250,8 @@ static void dmirror_device_evict_chunk(struct dmirror_chunk *chunk)
}
migrate_device_pages(src_pfns, dst_pfns, npages);
migrate_device_finalize(src_pfns, dst_pfns, npages);
kfree(src_pfns);
kfree(dst_pfns);
kvfree(src_pfns);
kvfree(dst_pfns);
}
/* Removes free pages from the free list so they can't be re-allocated */