From: "Edgecombe, Rick P" <rick.p.edgecombe@intel.com>
To: "Torvalds, Linus" <torvalds@linux-foundation.org>,
"npiggin@gmail.com" <npiggin@gmail.com>
Cc: "songliubraving@fb.com" <songliubraving@fb.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"daniel@iogearbox.net" <daniel@iogearbox.net>,
"hch@infradead.org" <hch@infradead.org>,
"ast@kernel.org" <ast@kernel.org>,
"bpf@vger.kernel.org" <bpf@vger.kernel.org>,
"Kernel-team@fb.com" <Kernel-team@fb.com>,
"linux-mm@kvack.org" <linux-mm@kvack.org>,
"rppt@kernel.org" <rppt@kernel.org>,
"song@kernel.org" <song@kernel.org>,
"pmladek@suse.com" <pmladek@suse.com>,
"akpm@linux-foundation.org" <akpm@linux-foundation.org>,
"hpa@zytor.com" <hpa@zytor.com>,
"edumazet@google.com" <edumazet@google.com>,
"bp@alien8.de" <bp@alien8.de>,
"mcgrof@kernel.org" <mcgrof@kernel.org>,
"mbenes@suse.cz" <mbenes@suse.cz>,
"imbrenda@linux.ibm.com" <imbrenda@linux.ibm.com>
Subject: Re: [PATCH v4 bpf 0/4] vmalloc: bpf: introduce VM_ALLOW_HUGE_VMAP
Date: Fri, 22 Apr 2022 20:22:32 +0000 [thread overview]
Message-ID: <63e73592b145e579b3eca984b5badc9300619077.camel@intel.com> (raw)
In-Reply-To: <b88a1097c994a72e9d8abfdcc43a4a0f9003d65a.camel@intel.com>
On Fri, 2022-04-22 at 10:10 -0700, Edgecombe, Richard P wrote:
> The risk this entails is racing against all the software page table
> walks and walking a freed table. At least on x86 the walks of the
> kernel tables are done with no locks, which works because the PTE
> updates are atomic and pretty much never freed. Some of the kernel
> page
> table walks in the fault handler are actually triggerable from
> userspace.
Argh, please ignore this. I guess interrupts getting disabled in the
fault handler forces the freeing of the page table to synchronize with
the fault handler walks via the TLB flush IPIs that precede the free.
Sorry for the noise.
next prev parent reply other threads:[~2022-04-22 21:55 UTC|newest]
Thread overview: 61+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-04-15 16:44 [PATCH v4 bpf 0/4] vmalloc: bpf: introduce VM_ALLOW_HUGE_VMAP Song Liu
2022-04-15 16:44 ` [PATCH v4 bpf 1/4] vmalloc: replace VM_NO_HUGE_VMAP with VM_ALLOW_HUGE_VMAP Song Liu
2022-04-15 17:43 ` Rik van Riel
2022-04-15 16:44 ` [PATCH v4 bpf 2/4] page_alloc: use vmalloc_huge for large system hash Song Liu
2022-04-15 17:43 ` Rik van Riel
2022-04-25 7:07 ` Geert Uytterhoeven
2022-04-25 8:17 ` Linus Torvalds
2022-04-25 8:24 ` Geert Uytterhoeven
2022-04-15 16:44 ` [PATCH v4 bpf 3/4] module: introduce module_alloc_huge Song Liu
2022-04-15 18:06 ` Rik van Riel
2022-06-16 16:10 ` Dave Hansen
2022-04-15 16:44 ` [PATCH v4 bpf 4/4] bpf: use module_alloc_huge for bpf_prog_pack Song Liu
2022-04-15 19:05 ` [PATCH v4 bpf 0/4] vmalloc: bpf: introduce VM_ALLOW_HUGE_VMAP Luis Chamberlain
2022-04-16 1:34 ` Song Liu
2022-04-16 1:42 ` Luis Chamberlain
2022-04-16 1:43 ` Luis Chamberlain
2022-04-16 5:08 ` Christoph Hellwig
2022-04-16 19:55 ` Song Liu
2022-04-16 20:30 ` Linus Torvalds
2022-04-16 22:26 ` Song Liu
2022-04-18 10:06 ` Mike Rapoport
2022-04-19 0:44 ` Luis Chamberlain
2022-04-19 1:56 ` Edgecombe, Rick P
2022-04-19 5:36 ` Song Liu
2022-04-19 18:42 ` Mike Rapoport
2022-04-19 19:20 ` Linus Torvalds
2022-04-20 2:03 ` Alexei Starovoitov
2022-04-20 2:18 ` Linus Torvalds
2022-04-20 14:42 ` Song Liu
2022-04-20 18:28 ` Luis Chamberlain
2022-04-21 7:29 ` Song Liu
2022-04-21 3:25 ` Nicholas Piggin
2022-04-21 5:48 ` Linus Torvalds
2022-04-21 6:02 ` Linus Torvalds
2022-04-21 9:07 ` Nicholas Piggin
2022-04-21 8:57 ` Nicholas Piggin
2022-04-21 15:44 ` Linus Torvalds
2022-04-21 23:30 ` Nicholas Piggin
2022-04-22 0:49 ` Linus Torvalds
2022-04-22 1:51 ` Nicholas Piggin
2022-04-22 2:31 ` Linus Torvalds
2022-04-22 2:57 ` Nicholas Piggin
2022-04-21 15:47 ` Edgecombe, Rick P
2022-04-21 16:15 ` Linus Torvalds
2022-04-22 0:12 ` Nicholas Piggin
2022-04-22 2:29 ` Edgecombe, Rick P
2022-04-22 2:47 ` Linus Torvalds
2022-04-22 16:54 ` Edgecombe, Rick P
2022-04-22 3:08 ` Nicholas Piggin
2022-04-22 4:31 ` Nicholas Piggin
2022-04-22 17:10 ` Edgecombe, Rick P
2022-04-22 20:22 ` Edgecombe, Rick P [this message]
2022-04-22 3:33 ` Nicholas Piggin
2022-04-21 9:47 ` Nicholas Piggin
2022-04-19 21:24 ` Luis Chamberlain
2022-04-19 23:58 ` Edgecombe, Rick P
2022-04-20 7:58 ` Petr Mladek
2022-04-19 18:20 ` Mike Rapoport
2022-04-24 17:43 ` Linus Torvalds
2022-04-25 6:48 ` Song Liu
2022-04-21 3:19 ` Nicholas Piggin
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