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[108.254.203.202]) by smtp.gmail.com with ESMTPSA id 46e09a7af769-6fb5b1f57a1sm1292995a34.46.2024.06.16.09.55.49 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Sun, 16 Jun 2024 09:55:49 -0700 (PDT) From: Doug Moore X-Google-Original-From: Doug Moore Message-ID: <29240b1e-6a8a-0bd5-f16f-322623d4b778@freebsd.org> Date: Sun, 16 Jun 2024 11:55:48 -0500 List-Id: Commit messages for the main branch of the src repository List-Archive: https://lists.freebsd.org/archives/dev-commits-src-main List-Help: List-Post: List-Subscribe: List-Unsubscribe: X-BeenThere: dev-commits-src-main@freebsd.org Sender: owner-dev-commits-src-main@FreeBSD.org MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; FreeBSD amd64; rv:102.0) Gecko/20100101 Thunderbird/102.10.0 Subject: Re: git: dd0e5c02ab13 - main - swap_pager: small improvement to find_least Content-Language: en-US To: Peter Holm Cc: src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-main@FreeBSD.org References: <202406111638.45BGcnhX099470@gitrepo.freebsd.org> In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-Spamd-Bar: ---- X-Rspamd-Pre-Result: action=no action; module=replies; Message is reply to one we originated X-Spamd-Result: default: False [-4.00 / 15.00]; REPLY(-4.00)[]; ASN(0.00)[asn:15169, ipnet:2607:f8b0::/32, country:US] X-Rspamd-Queue-Id: 4W2K081gPGz4Vnb Thank you, Peter.  That was a stupid mistake and I have now undone it. Doug On 6/16/24 07:13, Peter Holm wrote: > On Tue, Jun 11, 2024 at 04:38:49PM +0000, Doug Moore wrote: >> The branch main has been updated by dougm: >> >> URL: https://cgit.FreeBSD.org/src/commit/?id=dd0e5c02ab13b9eb240d42a71a8f41a8b036bd33 >> >> commit dd0e5c02ab13b9eb240d42a71a8f41a8b036bd33 >> Author: Doug Moore >> AuthorDate: 2024-06-11 16:36:23 +0000 >> Commit: Doug Moore >> CommitDate: 2024-06-11 16:36:23 +0000 >> >> swap_pager: small improvement to find_least >> >> Drop an unneeded test, a branch and a needless computation to save a >> few instructions. >> >> Reviewed by: kib >> Differential Revision: https://reviews.freebsd.org/D45558 >> --- >> sys/vm/swap_pager.c | 19 +++++++------------ >> 1 file changed, 7 insertions(+), 12 deletions(-) >> >> diff --git a/sys/vm/swap_pager.c b/sys/vm/swap_pager.c >> index a07a38481490..15f227457bba 100644 >> --- a/sys/vm/swap_pager.c > Doug, > > Here's an easy way to reproduce the issue: > > 12:43 ~ $ sort /dev/zero & > [1] 3650 > 12:43 ~ $ sort /dev/zero & > [2] 3651 > 12:43 ~ $ sort /dev/zero & > [3] 3652 > 12:43 ~ $ panic: Negative index: -16 > cpuid = 8 > time = 1718534645 > KDB: stack backtrace: > db_trace_self_wrapper() at db_trace_self_wrapper+0x2b/frame 0xfffffe010855fa50 > vpanic() at vpanic+0x13f/frame 0xfffffe010855fb80 > panic() at panic+0x43/frame 0xfffffe010855fbe0 > swap_pager_find_least() at swap_pager_find_least+0x105/frame 0xfffffe010855fc20 > vm_object_collapse() at vm_object_collapse+0x68b/frame 0xfffffe010855fca0 > vmspace_fork() at vmspace_fork+0xb68/frame 0xfffffe010855fd30 > fork1() at fork1+0x4f8/frame 0xfffffe010855fda0 > sys_fork() at sys_fork+0x54/frame 0xfffffe010855fe00 > amd64_syscall() at amd64_syscall+0x158/frame 0xfffffe010855ff30 > fast_syscall_common() at fast_syscall_common+0xf8/frame 0xfffffe010855ff30 > --- syscall (2, FreeBSD ELF64, fork), rip = 0xaba1c31565a, rsp = 0xaba1b0cecb8, rbp = 0xaba1b0cf220 --- > KDB: enter: panic > [ thread pid 3653 tid 100349 ] > Stopped at $0,0x104d5c2(%rip) > db> x/s version > version: FreeBSD 15.0-CURRENT #2 main-n270778-d26c565597b8-dirty: Sun Jun 16 12:32:39 CEST 2024\012 pho@mercat1.netperf.freebsd.org:/usr/src/sys/amd64/compile/PHO\012 > db> > > --- a/sys/vm/swap_pager.c > +++ b/sys/vm/swap_pager.c > @@ -2303,6 +2303,7 @@ swap_pager_find_least(vm_object_t object, vm_pindex_t pindex) > if (sb == NULL) > return (object->size); > for (i = pindex - sb->p; i < SWAP_META_PAGES; i++) { > + KASSERT((i >= 0), ("Negative index: %d", i)); > if (sb->d[i] != SWAPBLK_NONE) > return (sb->p + i); > } > > - Peter