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h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=a7iLWY4QB8QkFuzmIeDOuDWqi+s4PDrdRofCrcgpwk7g0s79ucMCB53kHVem1hj2T pSQCImk33dpBgQBRs2a5GPjNO98tgnqSqiwrUjeWuJ5Tt9BG/N4hCvQsUw154sQYGh pPozkR//I3ob+wI5OyOxh8kYU1kfwlNXCDM5b8RY= Message-ID: <440a7ae5-7070-46d2-8644-3fc2fa6a707f@arm.com> Date: Mon, 27 Apr 2026 09:08:53 +0530 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v3 1/3] vmalloc: add __GFP_SKIP_KASAN support To: Catalin Marinas Cc: arnd@arndb.de, kees@kernel.org, mingo@redhat.com, peterz@infradead.org, juri.lelli@redhat.com, vincent.guittot@linaro.org, akpm@linux-foundation.org, david@kernel.org, urezki@gmail.com, dietmar.eggemann@arm.com, rostedt@goodmis.org, bsegall@google.com, mgorman@suse.de, vschneid@redhat.com, ljs@kernel.org, Liam.Howlett@oracle.com, vbabka@kernel.org, rppt@kernel.org, surenb@google.com, mhocko@suse.com, tglx@kernel.org, usama.anjum@arm.com, mathieu.desnoyers@efficios.com, linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, Ryan Roberts References: <20260424130157.3163009-1-dev.jain@arm.com> <20260424130157.3163009-2-dev.jain@arm.com> Content-Language: en-US From: Dev Jain In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspam-User: X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: B6A4D1C0008 X-Stat-Signature: qgpi96d5g9m1h1fcpyj88ecema5cjjbo X-HE-Tag: 1777261158-722412 X-HE-Meta: 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 eVJj0YBO K1yRdZcEYN3ZblnJJ7vEGtG90QC8IdBRlYP7xxYs8tShOX2Br4S8bvsHNKjHxG49WKpnFrh4499kCAkp986fXgNrmXoMF1H1G/3IXUIjJgKPl35EM/L8F0MofH00pTiqvUWiozBGlfcUODpIFtQ9jyl5pdr8Tbs725rIByd38WK1OEW6I9W2s4SD2wAINrn2t4ImyOdV5mIe4zLY+Nnkk46PY610lA0/6jcTv6oPYl7OjEOPJZW+O8CR3cOpTe/BTcazZo8ADdWje+zRrX0Jtq8bd0A== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 25/04/26 2:44 pm, Catalin Marinas wrote: > On Fri, Apr 24, 2026 at 06:31:55PM +0530, Dev Jain wrote: >> diff --git a/mm/vmalloc.c b/mm/vmalloc.c >> index b31b208f6ecb3..c94fcb2725b6b 100644 >> --- a/mm/vmalloc.c >> +++ b/mm/vmalloc.c >> @@ -3939,7 +3939,7 @@ static void *__vmalloc_area_node(struct vm_struct *area, gfp_t gfp_mask, >> __GFP_NOFAIL | __GFP_ZERO |\ >> __GFP_NORETRY | __GFP_RETRY_MAYFAIL |\ >> GFP_NOFS | GFP_NOIO | GFP_KERNEL_ACCOUNT |\ >> - GFP_USER | __GFP_NOLOCKDEP) >> + GFP_USER | __GFP_NOLOCKDEP | __GFP_SKIP_KASAN) >> >> static gfp_t vmalloc_fix_flags(gfp_t flags) >> { >> @@ -3980,6 +3980,9 @@ static gfp_t vmalloc_fix_flags(gfp_t flags) >> * >> * %__GFP_NOWARN can be used to suppress failure messages. >> * >> + * %__GFP_SKIP_KASAN can be used to skip unpoisoning of mapped pages >> + * (when prot=%PAGE_KERNEL). > > I just realised, if we go with this flag for vmalloc(), there's also a > comment in gfp_types.h implying that pages are unpoisoned by > kasan_unpoison_vmalloc() instead. This is no longer the case with this > patch. > > A VM_SKIP_KASAN flag may have been nicer but we already have > THREADINFO_GFP and GFP_VMAP_STACK, so all those call sites would have to > be moved to call the lower-level __vmalloc_node_range(). Yep we were discussing this only on v2, and realized the wider cleanup is not trivial and should be made separately. But I should change the documentation of GFP_SKIP_KASAN to say that if it passed on to vmalloc then it will also skip unpoisoning. >