From: Oleg Nesterov <oleg@redhat.com>
To: Gargi Sharma <gs051095@gmail.com>
Cc: linux-kernel@vger.kernel.org, riel@surriel.com,
julia.lawall@lip6.fr, akpm@linux-foundation.org,
mingo@kernel.org, pasha.tatashin@oracle.com,
ktkhai@virtuozzo.com
Subject: Re: [PATCH v2 2/2] pid: Remove pidhash
Date: Wed, 27 Sep 2017 17:45:43 +0200 [thread overview]
Message-ID: <20170927154543.GA3788@redhat.com> (raw)
In-Reply-To: <cad572fe8ee85b34851e277456a694d4e2a9de2f.1506488388.git.gs051095@gmail.com>
On 09/27, Gargi Sharma wrote:
>
> -#define find_next_offset(map, off) \
> - find_next_zero_bit((map)->page, BITS_PER_PAGE, off)
> -
this should go into the previous patch, but this is minor...
> @@ -208,12 +200,10 @@ struct pid *alloc_pid(struct pid_namespace *ns)
>
> upid = pid->numbers + ns->level;
> spin_lock_irq(&pidmap_lock);
> - if (!(ns->nr_hashed & PIDNS_HASH_ADDING))
> + if (!(ns->pid_allocated & PIDNS_ADDING))
> goto out_unlock;
> for ( ; upid >= pid->numbers; --upid) {
> - hlist_add_head_rcu(&upid->pid_chain,
> - &pid_hash[pid_hashfn(upid->nr, upid->ns)]);
> - upid->ns->nr_hashed++;
> + upid->ns->pid_allocated++;
No, this is wrong.
It is too late to check PIDNS_HASH_ADDING/PIDNS_ADDING and increment pid_allocated,
once we call idr_alloc_cyclic() this pid is already "hashed" in that it can be found
by find_pid_ns() with this patch applied.
And of course, it is too late to do atomic_set(&pid->count, 1) and initialize
pid->tasks[type] lists by the same reason.
Oleg.
next prev parent reply other threads:[~2017-09-27 15:45 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-09-27 5:06 [PATCH v2 0/2] Replace PID bitmap allocation with IDR API Gargi Sharma
2017-09-27 5:06 ` [PATCH v2 1/2] pid: Replace pid bitmap implementation " Gargi Sharma
2017-09-27 13:09 ` Rik van Riel
2017-09-27 14:06 ` Oleg Nesterov
2017-09-27 15:06 ` Gargi Sharma
2017-09-27 15:15 ` Oleg Nesterov
2017-09-27 15:05 ` Gargi Sharma
2017-09-27 15:05 ` Oleg Nesterov
2017-10-01 9:15 ` Christoph Hellwig
2017-10-01 10:35 ` Gargi Sharma
2017-10-02 13:14 ` Rik van Riel
2017-10-02 13:05 ` Rik van Riel
2017-09-27 5:06 ` [PATCH v2 2/2] pid: Remove pidhash Gargi Sharma
2017-09-27 15:45 ` Oleg Nesterov [this message]
2017-09-27 16:28 ` Oleg Nesterov
2017-09-30 15:41 ` Gargi Sharma
2017-10-02 15:03 ` Oleg Nesterov
2017-10-02 13:35 ` Rik van Riel
2017-10-02 13:45 ` Rik van Riel
2017-10-02 15:21 ` Oleg Nesterov
2017-10-02 15:22 ` Rik van Riel
2017-10-02 16:27 ` Gargi Sharma
2017-09-27 17:18 ` [PATCH v2 0/2] Replace PID bitmap allocation with IDR API Eric W. Biederman
[not found] ` <CAOCi2DESqWV2YPcRTe6NYjx6m6N19ewXbAyfLfeBa23kJiEO9Q@mail.gmail.com>
2017-09-28 19:46 ` Rik van Riel
2017-09-28 20:05 ` Gargi Sharma
2017-09-29 0:35 ` Rik van Riel
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