From: Al Viro <viro@zeniv.linux.org.uk>
To: david laight <david.laight@runbox.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
akpm@linux-foundation.org, linux-kernel@vger.kernel.org,
linux-mm@kvack.org, linux-alpha@vger.kernel.org
Subject: Re: [RFC][alpha] saner vmalloc handling (was Re: [Bug report] hash_name() may cross page boundary and trigger sleep in RCU context)
Date: Sun, 30 Nov 2025 16:43:48 +0000 [thread overview]
Message-ID: <20251130164348.GV3538@ZenIV> (raw)
In-Reply-To: <20251130113213.40c8e7a0@pumpkin>
On Sun, Nov 30, 2025 at 11:32:13AM +0000, david laight wrote:
> How difficult would it be to allocate the pte for the next 8GB on demand
> inside vmalloc(), and then propagate it to the per-task page tables.
> That is a path than can sleep, so being slow if it needs to synchronise
> with other cpu shouldn't matter - especially since it won't happen often.
>
> That should be moderately generic code and would let the vmalloc limit
> be 'soft'; perhaps based on physical memory size, and even be raisable
> from a sysctl.
Considerable headache and pretty pointless, at that. Note that >8G vmalloc
space on alpha had been racy all along (and known to be that); it was
basically "could we squeeze more out of khttpd" kind of fun.
Do we have realistic vmalloc-crazy loads with high fragmentation of vmalloc
space and total footprint worth bothering with that?
next prev parent reply other threads:[~2025-11-30 16:43 UTC|newest]
Thread overview: 65+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-11-26 9:05 [Bug report] hash_name() may cross page boundary and trigger sleep in RCU context Zizhi Wo
2025-11-26 10:19 ` [RFC PATCH] vfs: Fix might sleep in load_unaligned_zeropad() with rcu read lock held Xie Yuanbin
2025-11-26 18:10 ` Al Viro
2025-11-26 18:48 ` Al Viro
2025-11-26 19:05 ` Russell King (Oracle)
2025-11-26 19:26 ` Al Viro
2025-11-26 19:51 ` Russell King (Oracle)
2025-11-26 20:02 ` Al Viro
2025-11-26 22:25 ` david laight
2025-11-26 23:51 ` Al Viro
2025-11-26 23:31 ` Russell King (Oracle)
2025-11-27 3:03 ` Xie Yuanbin
2025-11-27 7:20 ` Sebastian Andrzej Siewior
2025-11-27 11:20 ` Xie Yuanbin
2025-11-28 1:39 ` Xie Yuanbin
2025-11-26 20:42 ` Al Viro
2025-11-26 10:27 ` [Bug report] hash_name() may cross page boundary and trigger sleep in RCU context Zizhi Wo
2025-11-26 21:12 ` Linus Torvalds
2025-11-27 10:27 ` Will Deacon
2025-11-27 10:57 ` Russell King (Oracle)
2025-11-28 17:06 ` Linus Torvalds
2025-11-29 1:01 ` Zizhi Wo
2025-11-29 1:35 ` Linus Torvalds
2025-11-29 4:08 ` [Bug report] hash_name() may cross page boundary and trigger Xie Yuanbin
2025-11-29 9:08 ` Al Viro
2025-11-29 9:25 ` Xie Yuanbin
2025-11-29 9:44 ` Al Viro
2025-11-29 10:05 ` Xie Yuanbin
2025-11-29 10:45 ` david laight
2025-11-29 8:54 ` [Bug report] hash_name() may cross page boundary and trigger sleep in RCU context Al Viro
2025-12-01 2:08 ` Zizhi Wo
2025-11-29 2:18 ` [Bug report] hash_name() may cross page boundary and trigger Xie Yuanbin
2025-12-01 13:28 ` [Bug report] hash_name() may cross page boundary and trigger sleep in RCU context Will Deacon
2025-12-02 12:43 ` Russell King (Oracle)
2025-12-02 13:02 ` Xie Yuanbin
2025-12-02 22:07 ` Linus Torvalds
2025-12-03 1:48 ` Xie Yuanbin
2025-12-05 12:08 ` Russell King (Oracle)
2025-12-08 2:32 ` Xie Yuanbin
2025-12-08 9:26 ` David Laight
2025-12-08 10:07 ` Russell King (Oracle)
2025-12-08 13:18 ` Xie Yuanbin
2025-12-08 15:43 ` Russell King (Oracle)
2025-12-09 1:30 ` Xie Yuanbin
2025-11-26 18:55 ` Al Viro
2025-11-27 2:24 ` Zizhi Wo
2025-11-29 3:37 ` Al Viro
2025-11-30 3:01 ` [RFC][alpha] saner vmalloc handling (was Re: [Bug report] hash_name() may cross page boundary and trigger sleep in RCU context) Al Viro
2025-11-30 11:32 ` david laight
2025-11-30 16:43 ` Al Viro [this message]
2025-11-30 18:14 ` Magnus Lindholm
2025-11-30 19:03 ` david laight
2025-11-30 20:31 ` Al Viro
2025-11-30 20:32 ` Al Viro
2025-11-30 22:16 ` Linus Torvalds
2025-11-30 23:37 ` Al Viro
2025-12-01 2:03 ` [Bug report] hash_name() may cross page boundary and trigger sleep in RCU context Zizhi Wo
2025-11-27 12:59 ` Will Deacon
2025-11-28 1:17 ` Zizhi Wo
2025-11-28 1:18 ` Zizhi Wo
2025-11-28 1:39 ` Zizhi Wo
2025-11-28 12:25 ` Will Deacon
2025-11-29 1:02 ` Zizhi Wo
2025-11-29 3:55 ` Al Viro
2025-12-01 2:38 ` Zizhi Wo
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