The patch titled
Subject: lib/test_hmm.c: handle src_pfns and dst_pfns allocation failure
has been added to the -mm mm-unstable branch. Its filename is
lib-test_hmmc-handle-src_pfns-and-dst_pfns-allocation-failure.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/lib-test_hmmc-handle-src_pfns-and-dst_pfns-allocation-failure.patch
This patch will later appear in the mm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: Duoming Zhou <duoming@xxxxxxxxxx>
Subject: lib/test_hmm.c: handle src_pfns and dst_pfns allocation failure
Date: Tue, 12 Mar 2024 08:59:05 +0800
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@xxxxxxxxxx
Fixes: b2ef9f5a5cb3 ("mm/hmm/test: add selftest driver for HMM")
Signed-off-by: Duoming Zhou <duoming@xxxxxxxxxx>
Cc: Jérôme Glisse <jglisse@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
lib/test_hmm.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)
--- a/lib/test_hmm.c~lib-test_hmmc-handle-src_pfns-and-dst_pfns-allocation-failure
+++ a/lib/test_hmm.c
@@ -1226,8 +1226,8 @@ static void dmirror_device_evict_chunk(s
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(s
}
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 */
_
Patches currently in -mm which might be from duoming@xxxxxxxxxx are
lib-test_hmmc-handle-src_pfns-and-dst_pfns-allocation-failure.patch
