From: Sukadev Bhattiprolu <sukadev-23VcF4HTsmIX0ybBhKVfKdBPR1lH4CV8@public.gmane.org>
To: Matt Helsley <matthltc-r/Jw6+rmf7HQT0dZR+AlfA@public.gmane.org>
Cc: containers-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org
Subject: Re: [RFC][PATCH 1/7] Factor out code to allocate pidmap page
Date: Mon, 4 May 2009 11:27:43 -0700 [thread overview]
Message-ID: <20090504182743.GA31892@linux.vnet.ibm.com> (raw)
In-Reply-To: <20090504182059.GN11734-r/Jw6+rmf7HQT0dZR+AlfA@public.gmane.org>
| OK, I'm having trouble not with your patch but the original code. This
| test of map->page outside the spinlock looks like an incorrect fix to a
| race. If map->page can be NULL right after we release the lock then it
| can become NULL after this test just as easily.
The map->page is not freed once allocated (free_pidmap() does not free
the page). I guess the point is if you exceeded 32K pids (one page worth
of pids) once, you would exceed it again; so no point freeing the page
and reallocating the next time.
Sukadev
prev parent reply other threads:[~2009-05-04 18:27 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-05-04 8:17 [RFC][PATCH 1/7] Factor out code to allocate pidmap page sukadev-23VcF4HTsmIX0ybBhKVfKdBPR1lH4CV8
[not found] ` <12414250653025-git-send-email-sukadev-23VcF4HTsmIX0ybBhKVfKdBPR1lH4CV8@public.gmane.org>
2009-05-04 8:17 ` [RFC][PATCH 2/7] Have alloc_pidmap() return actual error code sukadev-23VcF4HTsmIX0ybBhKVfKdBPR1lH4CV8
[not found] ` <1241425065670-git-send-email-sukadev-23VcF4HTsmIX0ybBhKVfKdBPR1lH4CV8@public.gmane.org>
2009-05-04 18:11 ` Matt Helsley
[not found] ` <20090504181111.GM11734-r/Jw6+rmf7HQT0dZR+AlfA@public.gmane.org>
2009-05-04 18:29 ` Sukadev Bhattiprolu
2009-05-04 8:17 ` [RFC][PATCH 3/7] Add target_pid parameter to alloc_pidmap() sukadev-23VcF4HTsmIX0ybBhKVfKdBPR1lH4CV8
[not found] ` <12414250651744-git-send-email-sukadev-23VcF4HTsmIX0ybBhKVfKdBPR1lH4CV8@public.gmane.org>
2009-05-04 20:03 ` Serge E. Hallyn
[not found] ` <20090504200318.GA29491-r/Jw6+rmf7HQT0dZR+AlfA@public.gmane.org>
2009-05-05 22:23 ` Sukadev Bhattiprolu
[not found] ` <20090505222342.GB20515-23VcF4HTsmIX0ybBhKVfKdBPR1lH4CV8@public.gmane.org>
2009-05-05 23:01 ` Serge E. Hallyn
2009-05-04 8:17 ` [RFC][PATCH 4/7] Add target_pids parameter to alloc_pid() sukadev-23VcF4HTsmIX0ybBhKVfKdBPR1lH4CV8
2009-05-04 8:17 ` [RFC][PATCH 5/7] Add target_pids parameter to copy_process() sukadev-23VcF4HTsmIX0ybBhKVfKdBPR1lH4CV8
2009-05-04 8:17 ` [RFC][PATCH 6/7] Define do_fork_with_pids() sukadev-23VcF4HTsmIX0ybBhKVfKdBPR1lH4CV8
[not found] ` <12414250652549-git-send-email-sukadev-23VcF4HTsmIX0ybBhKVfKdBPR1lH4CV8@public.gmane.org>
2009-05-04 18:26 ` Matt Helsley
[not found] ` <20090504182621.GO11734-r/Jw6+rmf7HQT0dZR+AlfA@public.gmane.org>
2009-05-04 18:32 ` Sukadev Bhattiprolu
2009-05-04 8:17 ` [RFC][PATCH 7/7] Define clone_with_pids syscall sukadev-23VcF4HTsmIX0ybBhKVfKdBPR1lH4CV8
2009-05-04 18:20 ` [RFC][PATCH 1/7] Factor out code to allocate pidmap page Matt Helsley
[not found] ` <20090504182059.GN11734-r/Jw6+rmf7HQT0dZR+AlfA@public.gmane.org>
2009-05-04 18:27 ` Sukadev Bhattiprolu [this message]
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