From: Maurizio Lombardi <mlombard@redhat.com>
To: Alexander Duyck <alexander.duyck@gmail.com>
Cc: "Jakub Kicinski" <kuba@kernel.org>,
"Andrew Morton" <akpm@linux-foundation.org>,
linux-mm <linux-mm@kvack.org>,
LKML <linux-kernel@vger.kernel.org>,
Netdev <netdev@vger.kernel.org>, 愚树 <chen45464546@163.com>
Subject: Re: [PATCH] mm: prevent page_frag_alloc() from corrupting the memory
Date: Mon, 11 Jul 2022 11:02:33 +0200 [thread overview]
Message-ID: <CAFL455nFxcrpezZENBHhMe_D7mE9N_v9mN9YjYQr1Z=-E3inug@mail.gmail.com> (raw)
In-Reply-To: <20220711075225.15687-1-mlombard@redhat.com>
Tested with this kernel module:
http://bsdbackstore.eu/misc/oomk/
It requires 2 parameters: the first one is the amount of memory you
want to allocate with page_frag_alloc(), the second one is the size of
the fragment
I tested it on a machine with ~7Gb of free memory.
Without the patch:
-------------------------------------------------
3Gb of memory will be used with frag size = 1024 byte. No issue:
#insmod oomk.ko memory_size_gb=3 fragsize=1024
[ 177.875107] Test begins, memory size = 3 fragsize = 1024
[ 177.974538] Test completed!
10 Gb of memory, 1024 byte frag. page allocation failure but the
kernel handles it and doesn't crash:
#insmod oomk.ko memory_size_gb=10 fragsize=1024
[ 215.104801] Test begins, memory size = 10 fragsize = 1024
[ 215.227854] insmod: page allocation failure: order:0,
mode:0xa20(GFP_ATOMIC), nodemask=(null),cpuset=/,mems_allowed=0
[ 215.230231] CPU: 1 PID: 1738 Comm: insmod Kdump: loaded Tainted: G
OE --------- --- 5.14.0-124.kpq0.el9.x86_64 #1
[ 215.232344] Hardware name: Red Hat KVM, BIOS 0.5.1 01/01/2011
[ 215.233523] Call Trace:
[ 215.234001] dump_stack_lvl+0x34/0x44
[ 215.234894] warn_alloc+0x134/0x160
[ 215.235592] __alloc_pages_slowpath.constprop.0+0x809/0x840
[ 215.236687] ? get_page_from_freelist+0xc6/0x500
[ 215.237569] __alloc_pages+0x1fa/0x230
[ 215.238381] page_frag_alloc_align+0x16c/0x1a0
[...]
[ 215.315722] allocation number 7379888 failed!
[ 215.426227] Test completed!
10Gb, 4097 byte frag. Kernel crashes:
#insmod oomk.ko memory_size_gb=10 fragsize=4097
[ 623.461505] BUG: Bad page state in process insmod pfn:10a80c
[ 623.462634] page:000000000654dc14 refcount:0 mapcount:0
mapping:000000007a56d6cd index:0x0 pfn:0x10a80c
[ 623.464401] memcg:ffff900343a5b501
[ 623.465058] aops:0xffff9003409e5d38 with invalid host inode 00003524480055f0
[ 623.466394] flags: 0x17ffffc0000000(node=0|zone=2|lastcpupid=0x1fffff)
[ 623.467632] raw: 0017ffffc0000000 dead000000000100 dead000000000122
ffff900346cf2900
[ 623.469069] raw: 0000000000000000 0000000000100010 00000000ffffffff
ffff900343a5b501
[ 623.470521] page dumped because: page still charged to cgroup
[...]
[ 626.632838] general protection fault, probably for non-canonical
address 0xdead000000000108: 0000 [#1] PREEMPT SMP PTI
[ 626.633913] ------------[ cut here ]------------
[ 626.639981] CPU: 0 PID: 722 Comm: agetty Kdump: loaded Tainted: G
B OE --------- --- 5.14.0-124.kpq0.el9.x86_64 #1
[ 626.640923] WARNING: CPU: 1 PID: 22 at mm/slub.c:4566 __ksize+0xc4/0xe0
[ 626.645018] Hardware name: Red Hat KVM, BIOS 0.5.1 01/01/2011
[ 626.645021] RIP: 0010:___slab_alloc+0x1b7/0x5c0
------------------------------------------
With the patch the kernel doesn't crash:
#insmod oomk.ko memory_size_gb=10 fragsize=4097
[ 4859.358496] Test begins, memory size = 10 fragsize = 4097
[ 4859.459674] allocation number 607754 failed!
[ 4859.495489] Test completed!
#insmod oomk.ko memory_size_gb=10 fragsize=40000
[ 8428.021491] Test begins, memory size = 10 fragsize = 40000
[ 8428.024308] allocation number 0 failed!
[ 8428.025709] Test completed!
Maurizio
next prev parent reply other threads:[~2022-07-11 9:02 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-07-11 7:52 Maurizio Lombardi
2022-07-11 9:02 ` Maurizio Lombardi [this message]
2022-07-11 15:34 ` Alexander Duyck
2022-07-11 16:17 ` Maurizio Lombardi
2022-07-11 18:23 ` Alexander Duyck
2022-07-11 18:36 ` Maurizio Lombardi
2022-07-13 14:58 Maurizio Lombardi
2022-07-13 15:01 ` Maurizio Lombardi
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='CAFL455nFxcrpezZENBHhMe_D7mE9N_v9mN9YjYQr1Z=-E3inug@mail.gmail.com' \
--to=mlombard@redhat.com \
--cc=akpm@linux-foundation.org \
--cc=alexander.duyck@gmail.com \
--cc=chen45464546@163.com \
--cc=kuba@kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=netdev@vger.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 a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox