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Tue, 02 Feb 2021 16:31:36 -0800 (PST) Date: Tue, 2 Feb 2021 16:31:33 -0800 Message-Id: <20210203003134.2422308-1-surenb@google.com> Mime-Version: 1.0 X-Mailer: git-send-email 2.30.0.365.g02bc693789-goog Subject: [PATCH 1/2] mm: replace BUG_ON in vm_insert_page with a return of an error From: Suren Baghdasaryan To: sumit.semwal@linaro.org Cc: akpm@linux-foundation.org, hch@infradead.org, lmark@codeaurora.org, labbott@redhat.com, Brian.Starkey@arm.com, john.stultz@linaro.org, christian.koenig@amd.com, cgoldswo@codeaurora.org, orjan.eide@arm.com, robin.murphy@arm.com, jajones@nvidia.com, minchan@kernel.org, hridya@google.com, sspatil@google.com, linux-media@vger.kernel.org, dri-devel@lists.freedesktop.org, linaro-mm-sig@lists.linaro.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, kernel-team@android.com, surenb@google.com Content-Type: text/plain; charset="UTF-8" X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: Replace BUG_ON(vma->vm_flags & VM_PFNMAP) in vm_insert_page with WARN_ON_ONCE and returning an error. This is to ensure users of the vm_insert_page that set VM_PFNMAP are notified of the wrong flag usage and get an indication of an error without panicing the kernel. This will help identifying drivers that need to clear VM_PFNMAP before using dmabuf system heap which is moving to use vm_insert_page. Suggested-by: Christoph Hellwig Signed-off-by: Suren Baghdasaryan --- mm/memory.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/mm/memory.c b/mm/memory.c index feff48e1465a..e503c9801cd9 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -1827,7 +1827,8 @@ int vm_insert_page(struct vm_area_struct *vma, unsigned long addr, return -EINVAL; if (!(vma->vm_flags & VM_MIXEDMAP)) { BUG_ON(mmap_read_trylock(vma->vm_mm)); - BUG_ON(vma->vm_flags & VM_PFNMAP); + if (WARN_ON_ONCE(vma->vm_flags & VM_PFNMAP)) + return -EINVAL; vma->vm_flags |= VM_MIXEDMAP; } return insert_page(vma, addr, page, vma->vm_page_prot); -- 2.30.0.365.g02bc693789-goog