From: "tip-bot2 for Joerg Roedel" <tip-bot2@linutronix.de>
To: linux-tip-commits@vger.kernel.org
Cc: Joerg Roedel <jroedel@suse.de>, Ingo Molnar <mingo@kernel.org>,
x86 <x86@kernel.org>, LKML <linux-kernel@vger.kernel.org>
Subject: [tip: x86/mm] x86/mm/64: Update comment in preallocate_vmalloc_pages()
Date: Sat, 15 Aug 2020 15:46:48 -0000 [thread overview]
Message-ID: <159750640830.3192.8167910620509487065.tip-bot2@tip-bot2> (raw)
In-Reply-To: <20200814151947.26229-3-joro@8bytes.org>
The following commit has been merged into the x86/mm branch of tip:
Commit-ID: 7a27ef5e83089090f3a4073a9157c862ef00acfc
Gitweb: https://git.kernel.org/tip/7a27ef5e83089090f3a4073a9157c862ef00acfc
Author: Joerg Roedel <jroedel@suse.de>
AuthorDate: Fri, 14 Aug 2020 17:19:47 +02:00
Committer: Ingo Molnar <mingo@kernel.org>
CommitterDate: Sat, 15 Aug 2020 13:56:16 +02:00
x86/mm/64: Update comment in preallocate_vmalloc_pages()
The comment explaining why 4-level systems only need to allocate on
the P4D level caused some confustion. Update it to better explain why
on 4-level systems the allocation on PUD level is necessary.
Signed-off-by: Joerg Roedel <jroedel@suse.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20200814151947.26229-3-joro@8bytes.org
---
arch/x86/mm/init_64.c | 15 ++++++++++-----
1 file changed, 10 insertions(+), 5 deletions(-)
diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c
index 777d835..b5a3fa4 100644
--- a/arch/x86/mm/init_64.c
+++ b/arch/x86/mm/init_64.c
@@ -1252,14 +1252,19 @@ static void __init preallocate_vmalloc_pages(void)
if (!p4d)
goto failed;
- /*
- * With 5-level paging the P4D level is not folded. So the PGDs
- * are now populated and there is no need to walk down to the
- * PUD level.
- */
if (pgtable_l5_enabled())
continue;
+ /*
+ * The goal here is to allocate all possibly required
+ * hardware page tables pointed to by the top hardware
+ * level.
+ *
+ * On 4-level systems, the P4D layer is folded away and
+ * the above code does no preallocation. Below, go down
+ * to the pud _software_ level to ensure the second
+ * hardware level is allocated on 4-level systems too.
+ */
lvl = "pud";
pud = pud_alloc(&init_mm, p4d, addr);
if (!pud)
prev parent reply other threads:[~2020-08-15 21:58 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-08-14 15:19 [PATCH 0/2] x86: Retry to remove vmalloc/ioremap synchronzation Joerg Roedel
2020-08-14 15:19 ` [PATCH 1/2] x86/mm/64: Do not sync vmalloc/ioremap mappings Joerg Roedel
2020-08-15 15:46 ` [tip: x86/mm] " tip-bot2 for Joerg Roedel
2020-08-14 15:19 ` [PATCH 2/2] x86/mm/64: Update comment in preallocate_vmalloc_pages() Joerg Roedel
2020-08-15 15:46 ` tip-bot2 for Joerg Roedel [this message]
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=159750640830.3192.8167910620509487065.tip-bot2@tip-bot2 \
--to=tip-bot2@linutronix.de \
--cc=jroedel@suse.de \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-tip-commits@vger.kernel.org \
--cc=mingo@kernel.org \
--cc=x86@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.