From: David Laight <[email protected]>
To: 'David Hildenbrand' <[email protected]>,
Greg KH <[email protected]>,
Al Viro <[email protected]>,
"Nick Desaulniers" <[email protected]>
Cc: Christoph Hellwig <[email protected]>,
"[email protected]" <[email protected]>,
Andrew Morton <[email protected]>,
"Jens Axboe" <[email protected]>, Arnd Bergmann <[email protected]>,
David Howells <[email protected]>,
"[email protected]"
<[email protected]>,
"[email protected]" <[email protected]>,
"[email protected]" <[email protected]>,
"[email protected]" <[email protected]>,
"[email protected]" <[email protected]>,
"[email protected]" <[email protected]>,
"[email protected]" <[email protected]>,
"[email protected]" <[email protected]>,
"[email protected]" <[email protected]>,
"[email protected]" <[email protected]>,
"[email protected]" <[email protected]>,
"[email protected]" <[email protected]>,
"[email protected]" <[email protected]>,
"[email protected]" <[email protected]>,
"[email protected]" <[email protected]>,
"[email protected]" <[email protected]>,
"[email protected]"
<[email protected]>
Subject: RE: Buggy commit tracked to: "Re: [PATCH 2/9] iov_iter: move rw_copy_check_uvector() into lib/iov_iter.c"
Date: Thu, 22 Oct 2020 09:02:54 +0000 [thread overview]
Message-ID: <[email protected]> (raw)
In-Reply-To: <[email protected]>
From: David Hildenbrand
> Sent: 22 October 2020 09:49
...
> >>> But, this looks now to be a compiler bug. I'm using the latest version
> >>> of clang and if I put "noinline" at the front of the function,
> >>> everything works.
> >>
> >> Well, the compiler can do more invasive optimizations when inlining. If
> >> you have buggy code that relies on some unspecified behavior, inlining
> >> can change the behavior ... but going over that code, there isn't too
> >> much action going on. At least nothing screamed at me.
> >
> > Apart from all the optimisations that get rid off the 'pass be reference'
> > parameters and strange conditional tests.
> > Plenty of scope for the compiler getting it wrong.
> > But nothing even vaguely illegal.
>
> Not the first time that people blame the compiler to then figure out
> that something else is wrong ... but maybe this time is different :)
Usually down to missing asm 'memory' constraints...
Need to read the obj file to see what the compiler did.
The code must be 'approximately right' or nothing would run.
So I'd guess it has to do with > 8 fragments.
David
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next prev parent reply other threads:[~2020-10-22 9:03 UTC|newest]
Thread overview: 66+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-25 4:51 let import_iovec deal with compat_iovecs as well v4 Christoph Hellwig
2020-09-25 4:51 ` [PATCH 1/9] compat.h: fix a spelling error in <linux/compat.h> Christoph Hellwig
2020-09-25 4:51 ` [PATCH 2/9] iov_iter: move rw_copy_check_uvector() into lib/iov_iter.c Christoph Hellwig
2020-10-21 16:13 ` Buggy commit tracked to: "Re: [PATCH 2/9] iov_iter: move rw_copy_check_uvector() into lib/iov_iter.c" Greg KH
2020-10-21 20:59 ` David Laight
2020-10-21 23:39 ` Al Viro
2020-10-22 8:26 ` Greg KH
2020-10-22 8:35 ` David Hildenbrand
2020-10-22 8:40 ` David Laight
2020-10-22 8:48 ` David Hildenbrand
2020-10-22 9:01 ` Greg KH
2020-10-22 9:06 ` David Laight
2020-10-22 9:19 ` David Hildenbrand
2020-10-22 9:25 ` David Hildenbrand
2020-10-22 9:32 ` David Laight
2020-10-22 9:36 ` David Hildenbrand
2020-10-22 10:48 ` Greg KH
2020-10-22 12:18 ` Greg KH
2020-10-22 12:42 ` David Hildenbrand
2020-10-22 12:57 ` Greg KH
2020-10-22 13:50 ` Greg KH
[not found] ` <CAK8P3a1B7OVdyzW0-97JwzZiwp0D0fnSfyete16QTvPp_1m07A@mail.gmail.com>
2020-10-22 14:40 ` Greg KH
2020-10-22 16:15 ` David Laight
2020-10-23 12:46 ` David Laight
2020-10-23 13:09 ` David Hildenbrand
2020-10-23 14:33 ` David Hildenbrand
2020-10-23 14:39 ` David Laight
2020-10-23 14:47 ` 'Greg KH'
2020-10-23 16:33 ` David Hildenbrand
2020-11-02 9:06 ` David Laight
2020-11-02 13:52 ` 'Greg KH'
2020-11-02 18:23 ` David Laight
2020-10-23 17:58 ` Al Viro
2020-10-23 18:27 ` Segher Boessenkool
2020-10-23 21:28 ` David Laight
2020-10-24 17:29 ` Segher Boessenkool
2020-10-24 21:12 ` David Laight
[not found] ` <CAK8P3a1n+b8hOMhNQSDzgic03dyXbmpccfTJ3C1bGKvzsgMXbg@mail.gmail.com>
2020-10-23 13:28 ` David Laight
2020-10-22 13:23 ` Christoph Hellwig
2020-10-22 16:35 ` David Laight
2020-10-22 16:40 ` Matthew Wilcox
2020-10-22 16:50 ` David Laight
2020-10-22 17:00 ` Nick Desaulniers
2020-10-22 20:59 ` Eric Biggers
2020-10-22 21:28 ` Al Viro
2020-10-22 18:19 ` Al Viro
2020-10-22 17:54 ` Nick Desaulniers
[not found] ` <CAK8P3a3LjG+ZvmQrkb9zpgov8xBkQQWrkHBPgjfYSqBKGrwT4w@mail.gmail.com>
2020-10-22 19:04 ` Nick Desaulniers
2020-10-22 19:24 ` Al Viro
2020-10-22 19:27 ` Al Viro
2020-10-22 20:06 ` Al Viro
2020-10-22 20:09 ` Al Viro
2020-10-22 20:11 ` Nick Desaulniers
2020-10-22 22:07 ` David Laight
2020-10-23 13:12 ` David Hildenbrand
2020-10-22 22:04 ` David Laight
2020-10-22 9:28 ` David Laight
2020-10-22 9:02 ` David Laight [this message]
2020-09-25 4:51 ` [PATCH 3/9] iov_iter: refactor rw_copy_check_uvector and import_iovec Christoph Hellwig
2020-09-25 4:51 ` [PATCH 4/9] iov_iter: transparently handle compat iovecs in import_iovec Christoph Hellwig
2020-09-25 4:51 ` [PATCH 5/9] fs: remove various compat readv/writev helpers Christoph Hellwig
2020-09-25 4:51 ` [PATCH 6/9] fs: remove the compat readv/writev syscalls Christoph Hellwig
2020-09-25 4:51 ` [PATCH 7/9] fs: remove compat_sys_vmsplice Christoph Hellwig
2020-09-25 4:51 ` [PATCH 8/9] mm: remove compat_process_vm_{readv,writev} Christoph Hellwig
2020-09-25 4:51 ` [PATCH 9/9] security/keys: remove compat_keyctl_instantiate_key_iov Christoph Hellwig
2020-09-25 15:23 ` let import_iovec deal with compat_iovecs as well v4 Al Viro
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