+ lib-test_hmmc-handle-src_pfns-and-dst_pfns-allocation-failure.patch added to mm-unstable branch

+ lib-test_hmmc-handle-src_pfns-and-dst_pfns-allocation-failure.patch added to mm-unstable branch

[Andrew Morton]

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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@zju.edu.cn>
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@zju.edu.cn
Fixes: b2ef9f5a5cb3 ("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>
---

 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@zju.edu.cn are

lib-test_hmmc-handle-src_pfns-and-dst_pfns-allocation-failure.patch