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Tue, 20 Dec 2022 10:53:18 -0800 (PST) Date: Tue, 20 Dec 2022 18:53:18 +0000 From: Lorenzo Stoakes To: "Uladzislau Rezki (Sony)" Cc: Andrew Morton , linux-mm@kvack.org, LKML , Baoquan He , Christoph Hellwig , Matthew Wilcox , Nicholas Piggin , Oleksiy Avramchenko Subject: Re: [PATCH 2/2] mm: vmalloc: Replace BUG_ON() by WARN_ON_ONCE() Message-ID: References: <20221220182704.181657-1-urezki@gmail.com> <20221220182704.181657-2-urezki@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20221220182704.181657-2-urezki@gmail.com> X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: 94E2F80003 X-Rspam-User: X-Stat-Signature: f8emc7jp3psy6zn1jpshfssbt5sxd534 X-HE-Tag: 1671562400-659569 X-HE-Meta: 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 /CU8mmPR Q1+vBJ9RiBCIZpVNe7LWx9P0Rk/XMsT5YGcpFBSFipQqnZ2VKOu6/CHbfa9glB+ghD9dSSC9M6c0y+pZSxOlW/qS7UJn72UacRtMIRXLVNRWdkO9U7hPuIShzaD463SNnGY0b 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: On Tue, Dec 20, 2022 at 07:27:04PM +0100, Uladzislau Rezki (Sony) wrote: > Currently a vm_unmap_ram() functions triggers a BUG() if an area > is not found. Replace it by the WARN_ON_ONCE() error message and > keep machine alive instead of stopping it. > > The worst case is a memory leaking. > > Signed-off-by: Uladzislau Rezki (Sony) > --- > mm/vmalloc.c | 10 ++++++---- > 1 file changed, 6 insertions(+), 4 deletions(-) > > diff --git a/mm/vmalloc.c b/mm/vmalloc.c > index 0fc38c36e0df..e05a0dc79ac5 100644 > --- a/mm/vmalloc.c > +++ b/mm/vmalloc.c > @@ -2255,10 +2255,12 @@ void vm_unmap_ram(const void *mem, unsigned int count) > } > > va = find_unlink_vmap_area(addr); > - BUG_ON(!va); > - debug_check_no_locks_freed((void *)va->va_start, > - (va->va_end - va->va_start)); > - free_unmap_vmap_area(va); > + > + if (!WARN_ON_ONCE(!va)) { > + debug_check_no_locks_freed((void *)va->va_start, > + (va->va_end - va->va_start)); > + free_unmap_vmap_area(va); > + } > } > EXPORT_SYMBOL(vm_unmap_ram); > > -- > 2.30.2 > Absolutely in favour of this in principle (BUG_ON() is something we should resort to in only the direst of circumstances), one small nit - perhaps it'd be neater to simply make this a guard clause? E.g.:- if (!WARN_ON_ONCE(!va)) return; ...