From: Ira Weiny <ira.weiny@intel.com>
To: Matthew Wilcox <willy@infradead.org>
Cc: Dave Hansen <dave.hansen@intel.com>,
Eric Biggers <ebiggers@kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
Andy Lutomirski <luto@kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
linux-aio@kvack.org, linux-efi@vger.kernel.org,
kvm@vger.kernel.org, linux-doc@vger.kernel.org,
linux-mmc@vger.kernel.org,
Dave Hansen <dave.hansen@linux.intel.com>,
dri-devel@lists.freedesktop.org, linux-mm@kvack.org,
target-devel@vger.kernel.org, linux-mtd@lists.infradead.org,
linux-kselftest@vger.kernel.org, samba-technical@lists.samba.org,
ceph-devel@vger.kernel.org, drbd-dev@lists.linbit.com,
devel@driverdev.osuosl.org, linux-cifs@vger.kernel.org,
linux-nilfs@vger.kernel.org, linux-scsi@vger.kernel.org,
linux-nvdimm@lists.01.org, linux-rdma@vger.kernel.org,
x86@kernel.org, amd-gfx@lists.freedesktop.org,
linux-afs@lists.infradead.org, cluster-devel@redhat.com,
linux-cachefs@redhat.com, intel-wired-lan@lists.osuosl.org,
xen-devel@lists.xenproject.org, linux-ext4@vger.kernel.org,
Fenghua Yu <fenghua.yu@intel.com>,
ecryptfs@vger.kernel.org, linux-um@lists.infradead.org,
intel-gfx@lists.freedesktop.org, linux-erofs@lists.ozlabs.org,
reiserfs-devel@vger.kernel.org, linux-block@vger.kernel.org,
linux-bcache@vger.kernel.org, Jaegeuk Kim <jaegeuk@kernel.org>,
Dan Williams <dan.j.williams@intel.com>,
io-uring@vger.kernel.org, linux-nfs@vger.kernel.org,
linux-ntfs-dev@lists.sourceforge.net, netdev@vger.kernel.org,
kexec@lists.infradead.org, linux-kernel@vger.kernel.org,
linux-f2fs-devel@lists.sourceforge.net,
linux-fsdevel@vger.kernel.org, bpf@vger.kernel.org,
linuxppc-dev@lists.ozlabs.org, linux-btrfs@vger.kernel.org
Subject: Re: [PATCH RFC PKS/PMEM 22/58] fs/f2fs: Utilize new kmap_thread()
Date: Mon, 12 Oct 2020 12:53:54 -0700 [thread overview]
Message-ID: <20201012195354.GC2046448@iweiny-DESK2.sc.intel.com> (raw)
In-Reply-To: <20201012164438.GA20115@casper.infradead.org>
On Mon, Oct 12, 2020 at 05:44:38PM +0100, Matthew Wilcox wrote:
> On Mon, Oct 12, 2020 at 09:28:29AM -0700, Dave Hansen wrote:
> > kmap_atomic() is always preferred over kmap()/kmap_thread().
> > kmap_atomic() is _much_ more lightweight since its TLB invalidation is
> > always CPU-local and never broadcast.
> >
> > So, basically, unless you *must* sleep while the mapping is in place,
> > kmap_atomic() is preferred.
>
> But kmap_atomic() disables preemption, so the _ideal_ interface would map
> it only locally, then on preemption make it global. I don't even know
> if that _can_ be done. But this email makes it seem like kmap_atomic()
> has no downsides.
And that is IIUC what Thomas was trying to solve.
Also, Linus brought up that kmap_atomic() has quirks in nesting.[1]
From what I can see all of these discussions support the need to have something
between kmap() and kmap_atomic().
However, the reason behind converting call sites to kmap_thread() are different
between Thomas' patch set and mine. Both require more kmap granularity.
However, they do so with different reasons and underlying implementations but
with the _same_ resulting semantics; a thread local mapping which is
preemptable.[2] Therefore they each focus on changing different call sites.
While this patch set is huge I think it serves a valuable purpose to identify a
large number of call sites which are candidates for this new semantic.
Ira
[1] https://lore.kernel.org/lkml/CAHk-=wgbmwsTOKs23Z=71EBTrULoeaH2U3TNqT2atHEWvkBKdw@mail.gmail.com/
[2] It is important to note these implementations are not incompatible with
each other. So I don't see yet another 'kmap_something()' being required.
next prev parent reply other threads:[~2020-10-12 19:54 UTC|newest]
Thread overview: 93+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-09 19:49 [PATCH RFC PKS/PMEM 00/58] PMEM: Introduce stray write protection for PMEM ira.weiny
2020-10-09 19:49 ` [PATCH RFC PKS/PMEM 01/58] x86/pks: Add a global pkrs option ira.weiny
2020-10-09 19:49 ` [PATCH RFC PKS/PMEM 02/58] x86/pks/test: Add testing for global option ira.weiny
2020-10-09 19:49 ` [PATCH RFC PKS/PMEM 03/58] memremap: Add zone device access protection ira.weiny
2020-10-09 19:49 ` [PATCH RFC PKS/PMEM 04/58] kmap: Add stray access protection for device pages ira.weiny
2020-10-09 19:49 ` [PATCH RFC PKS/PMEM 05/58] kmap: Introduce k[un]map_thread ira.weiny
2020-11-10 1:13 ` Thomas Gleixner
2020-11-10 4:59 ` Ira Weiny
2020-11-10 8:48 ` Thomas Gleixner
2020-10-09 19:49 ` [PATCH RFC PKS/PMEM 06/58] kmap: Introduce k[un]map_thread debugging ira.weiny
2020-10-09 19:49 ` [PATCH RFC PKS/PMEM 07/58] drivers/drbd: Utilize new kmap_thread() ira.weiny
2020-10-09 19:49 ` [PATCH RFC PKS/PMEM 08/58] drivers/firmware_loader: " ira.weiny
2020-10-09 19:49 ` [PATCH RFC PKS/PMEM 09/58] drivers/gpu: " ira.weiny
2020-10-09 22:03 ` Daniel Vetter
2020-10-10 23:01 ` Ira Weiny
2020-10-09 19:49 ` [PATCH RFC PKS/PMEM 10/58] drivers/rdma: " ira.weiny
2020-10-09 19:49 ` [PATCH RFC PKS/PMEM 11/58] drivers/net: " ira.weiny
2020-10-09 19:49 ` [PATCH RFC PKS/PMEM 12/58] fs/afs: " ira.weiny
2020-10-09 19:49 ` [PATCH RFC PKS/PMEM 13/58] fs/btrfs: " ira.weiny
2020-10-09 19:49 ` [PATCH RFC PKS/PMEM 14/58] fs/cifs: " ira.weiny
2020-10-09 19:49 ` [PATCH RFC PKS/PMEM 15/58] fs/ecryptfs: " ira.weiny
2020-10-09 19:49 ` [PATCH RFC PKS/PMEM 16/58] fs/gfs2: " ira.weiny
2020-10-09 19:49 ` [PATCH RFC PKS/PMEM 17/58] fs/nilfs2: " ira.weiny
2020-10-09 19:49 ` [PATCH RFC PKS/PMEM 18/58] fs/hfs: " ira.weiny
2020-10-09 19:49 ` [PATCH RFC PKS/PMEM 19/58] fs/hfsplus: " ira.weiny
2020-10-09 19:49 ` [PATCH RFC PKS/PMEM 20/58] fs/jffs2: " ira.weiny
2020-10-09 19:49 ` [PATCH RFC PKS/PMEM 21/58] fs/nfs: " ira.weiny
2020-10-09 19:49 ` [PATCH RFC PKS/PMEM 22/58] fs/f2fs: " ira.weiny
2020-10-09 21:34 ` Eric Biggers
2020-10-10 0:39 ` Matthew Wilcox
2020-10-10 1:30 ` Eric Biggers
2020-10-12 6:56 ` Ira Weiny
2020-10-12 16:19 ` Eric Biggers
2020-10-12 16:28 ` Dave Hansen
2020-10-12 16:44 ` Matthew Wilcox
2020-10-12 19:53 ` Ira Weiny [this message]
2020-10-12 20:02 ` Matthew Wilcox
2020-10-12 23:31 ` Ira Weiny
2020-10-10 2:43 ` James Bottomley
2020-10-09 19:49 ` [PATCH RFC PKS/PMEM 23/58] fs/fuse: " ira.weiny
2020-10-09 19:49 ` [PATCH RFC PKS/PMEM 24/58] fs/freevxfs: " ira.weiny
2020-10-13 11:25 ` Christoph Hellwig
2020-10-13 20:52 ` Ira Weiny
2020-10-09 19:50 ` [PATCH RFC PKS/PMEM 25/58] fs/reiserfs: " ira.weiny
2020-10-09 19:50 ` [PATCH RFC PKS/PMEM 26/58] fs/zonefs: " ira.weiny
2020-10-12 2:30 ` Damien Le Moal
2020-10-09 19:50 ` [PATCH RFC PKS/PMEM 27/58] fs/ubifs: " ira.weiny
2020-10-09 19:50 ` [PATCH RFC PKS/PMEM 28/58] fs/cachefiles: " ira.weiny
2020-10-09 19:50 ` [PATCH RFC PKS/PMEM 29/58] fs/ntfs: " ira.weiny
2020-10-09 19:50 ` [PATCH RFC PKS/PMEM 30/58] fs/romfs: " ira.weiny
2020-10-09 19:50 ` [PATCH RFC PKS/PMEM 31/58] fs/vboxsf: " ira.weiny
2020-10-09 19:50 ` [PATCH RFC PKS/PMEM 32/58] fs/hostfs: " ira.weiny
2020-10-09 19:50 ` [PATCH RFC PKS/PMEM 33/58] fs/cramfs: " ira.weiny
2020-10-13 18:36 ` Nicolas Pitre
2020-10-13 18:44 ` Dan Williams
2020-10-13 19:36 ` Matthew Wilcox
2020-10-13 19:41 ` Dan Williams
2020-10-13 20:01 ` Al Viro
2020-10-13 20:50 ` Ira Weiny
2020-10-13 20:45 ` Ira Weiny
2020-10-09 19:50 ` [PATCH RFC PKS/PMEM 34/58] fs/erofs: " ira.weiny
2020-10-09 19:50 ` [PATCH RFC PKS/PMEM 35/58] fs: " ira.weiny
2020-10-09 19:50 ` [PATCH RFC PKS/PMEM 36/58] fs/ext2: Use ext2_put_page ira.weiny
2020-10-09 19:50 ` [PATCH RFC PKS/PMEM 37/58] fs/ext2: Utilize new kmap_thread() ira.weiny
2020-10-09 19:50 ` [PATCH RFC PKS/PMEM 38/58] fs/isofs: " ira.weiny
2020-10-09 19:50 ` [PATCH RFC PKS/PMEM 39/58] fs/jffs2: " ira.weiny
2020-10-09 19:50 ` [PATCH RFC PKS/PMEM 40/58] net: " ira.weiny
2020-10-09 19:50 ` [PATCH RFC PKS/PMEM 41/58] drivers/target: " ira.weiny
2020-10-09 19:50 ` [PATCH RFC PKS/PMEM 42/58] drivers/scsi: " ira.weiny
2020-10-09 19:50 ` [PATCH RFC PKS/PMEM 43/58] drivers/mmc: " ira.weiny
2020-10-09 19:50 ` [PATCH RFC PKS/PMEM 44/58] drivers/xen: " ira.weiny
2020-10-09 19:50 ` [PATCH RFC PKS/PMEM 45/58] drivers/firmware: " ira.weiny
2020-10-09 19:50 ` [PATCH RFC PKS/PMEM 46/58] drives/staging: " ira.weiny
2020-10-09 19:50 ` [PATCH RFC PKS/PMEM 47/58] drivers/mtd: " ira.weiny
2020-10-09 19:50 ` [PATCH RFC PKS/PMEM 48/58] drivers/md: " ira.weiny
2020-10-10 2:20 ` Coly Li
2020-10-12 5:28 ` Ira Weiny
2020-10-12 7:40 ` Coly Li
2020-10-09 19:50 ` [PATCH RFC PKS/PMEM 49/58] drivers/misc: " ira.weiny
2020-10-09 19:50 ` [PATCH RFC PKS/PMEM 50/58] drivers/android: " ira.weiny
2020-10-09 19:50 ` [PATCH RFC PKS/PMEM 51/58] kernel: " ira.weiny
2020-10-10 3:43 ` Eric W. Biederman
2020-10-09 19:50 ` [PATCH RFC PKS/PMEM 52/58] mm: " ira.weiny
2020-10-09 19:50 ` [PATCH RFC PKS/PMEM 53/58] lib: " ira.weiny
2020-10-09 19:50 ` [PATCH RFC PKS/PMEM 54/58] powerpc: " ira.weiny
2020-10-09 19:50 ` [PATCH RFC PKS/PMEM 55/58] samples: " ira.weiny
2020-10-09 19:50 ` [PATCH RFC PKS/PMEM 56/58] dax: Stray access protection for dax_direct_access() ira.weiny
2020-10-09 19:50 ` [PATCH RFC PKS/PMEM 57/58] nvdimm/pmem: Stray access protection for pmem->virt_addr ira.weiny
2020-10-10 2:53 ` John Hubbard
2020-10-12 5:52 ` Ira Weiny
2020-10-09 19:50 ` [PATCH RFC PKS/PMEM 58/58] [dax|pmem]: Enable stray access protection ira.weiny
2020-10-10 11:36 ` [PATCH RFC PKS/PMEM 10/58] drivers/rdma: Utilize new kmap_thread() Bernard Metzler
2020-10-12 4:47 ` Ira Weiny
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=20201012195354.GC2046448@iweiny-DESK2.sc.intel.com \
--to=ira.weiny@intel.com \
--cc=akpm@linux-foundation.org \
--cc=amd-gfx@lists.freedesktop.org \
--cc=bp@alien8.de \
--cc=bpf@vger.kernel.org \
--cc=ceph-devel@vger.kernel.org \
--cc=cluster-devel@redhat.com \
--cc=dan.j.williams@intel.com \
--cc=dave.hansen@intel.com \
--cc=dave.hansen@linux.intel.com \
--cc=devel@driverdev.osuosl.org \
--cc=drbd-dev@lists.linbit.com \
--cc=dri-devel@lists.freedesktop.org \
--cc=ebiggers@kernel.org \
--cc=ecryptfs@vger.kernel.org \
--cc=fenghua.yu@intel.com \
--cc=intel-gfx@lists.freedesktop.org \
--cc=intel-wired-lan@lists.osuosl.org \
--cc=io-uring@vger.kernel.org \
--cc=jaegeuk@kernel.org \
--cc=kexec@lists.infradead.org \
--cc=kvm@vger.kernel.org \
--cc=linux-afs@lists.infradead.org \
--cc=linux-aio@kvack.org \
--cc=linux-bcache@vger.kernel.org \
--cc=linux-block@vger.kernel.org \
--cc=linux-btrfs@vger.kernel.org \
--cc=linux-cachefs@redhat.com \
--cc=linux-cifs@vger.kernel.org \
--cc=linux-doc@vger.kernel.org \
--cc=linux-efi@vger.kernel.org \
--cc=linux-erofs@lists.ozlabs.org \
--cc=linux-ext4@vger.kernel.org \
--cc=linux-f2fs-devel@lists.sourceforge.net \
--cc=linux-fsdevel@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-kselftest@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=linux-mmc@vger.kernel.org \
--cc=linux-mtd@lists.infradead.org \
--cc=linux-nfs@vger.kernel.org \
--cc=linux-nilfs@vger.kernel.org \
--cc=linux-ntfs-dev@lists.sourceforge.net \
--cc=linux-nvdimm@lists.01.org \
--cc=linux-rdma@vger.kernel.org \
--cc=linux-scsi@vger.kernel.org \
--cc=linux-um@lists.infradead.org \
--cc=linuxppc-dev@lists.ozlabs.org \
--cc=luto@kernel.org \
--cc=mingo@redhat.com \
--cc=netdev@vger.kernel.org \
--cc=peterz@infradead.org \
--cc=reiserfs-devel@vger.kernel.org \
--cc=samba-technical@lists.samba.org \
--cc=target-devel@vger.kernel.org \
--cc=tglx@linutronix.de \
--cc=willy@infradead.org \
--cc=x86@kernel.org \
--cc=xen-devel@lists.xenproject.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;
as well as URLs for NNTP newsgroup(s).