From: Michal Hocko <mhocko@suse.com>
To: Gregory Price <gourry.memverge@gmail.com>
Cc: linux-mm@kvack.org, linux-doc@vger.kernel.org,
linux-fsdevel@vger.kernel.org, linux-api@vger.kernel.org,
linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org,
akpm@linux-foundation.org, arnd@arndb.de, tglx@linutronix.de,
luto@kernel.org, mingo@redhat.com, bp@alien8.de,
dave.hansen@linux.intel.com, x86@kernel.org, hpa@zytor.com,
tj@kernel.org, ying.huang@intel.com,
Gregory Price <gregory.price@memverge.com>
Subject: Re: [RFC PATCH 05/11] mm/mempolicy: modify set_mempolicy_home_node to take a task argument
Date: Tue, 28 Nov 2023 15:07:38 +0100 [thread overview]
Message-ID: <ZWX0KkaUGJoUdmQS@tiehlicka> (raw)
In-Reply-To: <20231122211200.31620-6-gregory.price@memverge.com>
On Wed 22-11-23 16:11:54, Gregory Price wrote:
[...]
> +
> + /*
> + * Behavior when task == current allows a task modifying itself
> + * to bypass the check in get_task_mm and acquire the mm directly
> + */
> + if (task == current) {
> + mm = task->mm;
> + mmget(mm);
> + } else
> + mm = get_task_mm(task);
Similar question as in the previous patch. When is a kthread legit to do
manipulate borrowed mm memory policy?
> +
> + if (!mm)
> + return -ENODEV;
Is this an expected error? No mm means task dying and mm has been
already released. Should we simply return ESRCH wouldbe a better error
code IMO. This should never happen for the current task so it sould be
safe to add.
--
Michal Hocko
SUSE Labs
next prev parent reply other threads:[~2023-11-28 14:07 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-11-22 21:11 [RFC PATCH 00/11] mm/mempolicy: Make task->mempolicy externally modifiable via syscall and procfs Gregory Price
2023-11-22 21:11 ` [RFC PATCH 01/11] mm/mempolicy: refactor do_set_mempolicy for code re-use Gregory Price
2023-11-22 21:11 ` [RFC PATCH 02/11] mm/mempolicy: swap cond reference counting logic in do_get_mempolicy Gregory Price
2023-11-28 14:07 ` Michal Hocko
[not found] ` <ZWX0ytAwmOdooHdZ@memverge.com>
2023-11-28 14:28 ` Michal Hocko
2023-11-22 21:11 ` [RFC PATCH 03/11] mm/mempolicy: refactor set_mempolicy stack to take a task argument Gregory Price
2023-11-22 21:11 ` [RFC PATCH 04/11] mm/mempolicy: modify get_mempolicy call " Gregory Price
2023-11-28 14:07 ` Michal Hocko
[not found] ` <ZWX1U1gCTXC+lFXn@memverge.com>
2023-11-28 14:49 ` Michal Hocko
2023-11-22 21:11 ` [RFC PATCH 05/11] mm/mempolicy: modify set_mempolicy_home_node " Gregory Price
2023-11-28 14:07 ` Michal Hocko [this message]
2023-11-28 14:14 ` Gregory Price
2023-11-22 21:11 ` [RFC PATCH 06/11] mm/mempolicy: modify do_mbind to operate on task argument instead of current Gregory Price
2023-11-28 14:11 ` Michal Hocko
2023-11-28 14:51 ` Gregory Price
2023-11-28 18:08 ` Gregory Price
2023-11-22 21:11 ` [RFC PATCH 07/11] mm/mempolicy: add task mempolicy syscall variants Gregory Price
2023-11-22 21:11 ` [RFC PATCH 08/11] mm/mempolicy: export replace_mempolicy for use by procfs Gregory Price
2023-11-22 21:11 ` [RFC PATCH 09/11] mm/mempolicy: build mpol_parse_str unconditionally Gregory Price
2023-11-22 21:11 ` [RFC PATCH 10/11] mm/mempolicy: mpol_parse_str should ignore trailing characters in nodelist Gregory Price
2023-11-22 21:12 ` [RFC PATCH 11/11] fs/proc: Add mempolicy attribute to allow read/write of task mempolicy Gregory Price
2023-11-22 21:33 ` [RFC PATCH 00/11] mm/mempolicy: Make task->mempolicy externally modifiable via syscall and procfs Andrew Morton
2023-11-22 21:35 ` Andrew Morton
2023-11-22 22:24 ` Gregory Price
2023-11-27 15:29 ` Michal Hocko
2023-11-27 16:14 ` Gregory Price
2023-11-28 9:45 ` Michal Hocko
2023-11-28 13:15 ` Gregory Price
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