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[90.233.197.228]) by smtp.gmail.com with ESMTPSA id 2adb3069b0e04-59434454841sm844491e87.101.2025.11.04.08.28.18 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 04 Nov 2025 08:28:18 -0800 (PST) From: Uladzislau Rezki X-Google-Original-From: Uladzislau Rezki Date: Tue, 4 Nov 2025 17:28:16 +0100 To: "Vishal Moola (Oracle)" Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, Uladzislau Rezki , Andrew Morton , Christoph Hellwig Subject: Re: [RFC PATCH v2 1/4] mm/vmalloc: warn on invalid vmalloc gfp flags Message-ID: References: <20251103190429.104747-1-vishal.moola@gmail.com> <20251103190429.104747-2-vishal.moola@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20251103190429.104747-2-vishal.moola@gmail.com> X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: A286C1C000F X-Stat-Signature: pwomg9so4kzyiam84ogzey5cx6jkcfo3 X-Rspam-User: X-HE-Tag: 1762273701-634402 X-HE-Meta: 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 eSUC/MzV 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 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: List-Subscribe: List-Unsubscribe: On Mon, Nov 03, 2025 at 11:04:26AM -0800, Vishal Moola (Oracle) wrote: > Vmalloc explicitly supports a list of flags, but we never enforce them. > vmalloc has been trying to handle unsupported flags by clearing and > setting flags wherever necessary. This is messy and makes the code > harder to understand, when we could simply check for a supported input > immediately instead. > > Define a helper mask and function telling callers they have passed in > invalid flags, and clear those unsupported vmalloc flags. > > Suggested-by: Christoph Hellwig > Signed-off-by: Vishal Moola (Oracle) > --- > mm/vmalloc.c | 24 ++++++++++++++++++++++++ > 1 file changed, 24 insertions(+) > > diff --git a/mm/vmalloc.c b/mm/vmalloc.c > index 0832f944544c..290016c7fb58 100644 > --- a/mm/vmalloc.c > +++ b/mm/vmalloc.c > @@ -3911,6 +3911,26 @@ static void *__vmalloc_area_node(struct vm_struct *area, gfp_t gfp_mask, > return NULL; > } > > +/* > + * See __vmalloc_node_range() for a clear list of supported vmalloc flags. > + * This gfp lists all flags currently passed through vmalloc. Currently, > + * __GFP_ZERO is used by BFP and __GFP_NORETRY is used by percpu. > + */ > +#define GFP_VMALLOC_SUPPORTED (GFP_KERNEL | GFP_ATOMIC | GFP_NOWAIT |\ > + __GFP_NOFAIL | __GFP_ZERO | __GFP_NORETRY) > + > +static gfp_t vmalloc_fix_flags(gfp_t flags) > +{ > + gfp_t invalid_mask = flags & ~GFP_VMALLOC_SUPPORTED; > + > + flags &= GFP_VMALLOC_SUPPORTED; > + pr_warn("Unexpected gfp: %#x (%pGg). Fixing up to gfp: %#x (%pGg). Fix your code!\n", > + invalid_mask, &invalid_mask, flags, &flags); > + dump_stack(); > WARN_ON() or friends? It prints the stack. > + > + return flags; > +} > + > /** > * __vmalloc_node_range - allocate virtually contiguous memory > * @size: allocation size > @@ -4092,6 +4112,8 @@ EXPORT_SYMBOL_GPL(__vmalloc_node_noprof); > > void *__vmalloc_noprof(unsigned long size, gfp_t gfp_mask) > { > + if (gfp_mask & ~GFP_VMALLOC_SUPPORTED) > + gfp_mask = vmalloc_fix_flags(gfp_mask); > return __vmalloc_node_noprof(size, 1, gfp_mask, NUMA_NO_NODE, > __builtin_return_address(0)); > } > @@ -4131,6 +4153,8 @@ EXPORT_SYMBOL(vmalloc_noprof); > */ > void *vmalloc_huge_node_noprof(unsigned long size, gfp_t gfp_mask, int node) > { > + if (gfp_mask & ~GFP_VMALLOC_SUPPORTED) > + gfp_mask = vmalloc_fix_flags(gfp_mask); > gfp_mask = check_and_fix_flags()? -- Uladzislau Rezki