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From: Linus Torvalds <torvalds@linux-foundation.org>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Alexander Duyck <alexander.h.duyck@linux.intel.com>,
	Jens Axboe <axboe@kernel.dk>,  Brian Geffon <bgeffon@google.com>,
	Christian Brauner <christian.brauner@ubuntu.com>,
	 Christian Brauner <christian@brauner.io>,
	Daniel Colascione <dancol@google.com>,
	 Johannes Weiner <hannes@cmpxchg.org>,
	Jann Horn <jannh@google.com>, John Dias <joaodias@google.com>,
	 Joel Fernandes <joel@joelfernandes.org>,
	Kirill Tkhai <ktkhai@virtuozzo.com>,
	 linux-man <linux-man@vger.kernel.org>,
	Linux-MM <linux-mm@kvack.org>,  Michal Hocko <mhocko@suse.com>,
	Minchan Kim <minchan@kernel.org>,
	mm-commits@vger.kernel.org,
	 Oleksandr Natalenko <oleksandr@redhat.com>,
	David Rientjes <rientjes@google.com>,
	 Shakeel Butt <shakeelb@google.com>,
	sj38.park@gmail.com, sjpark@amazon.de,
	 Sonny Rao <sonnyrao@google.com>,
	Sandeep Patil <sspatil@google.com>,
	 Suren Baghdasaryan <surenb@google.com>,
	Tim Murray <timmurray@google.com>,
	 Vlastimil Babka <vbabka@suse.cz>
Subject: Re: [patch 18/39] mm/madvise: check fatal signal pending of target process
Date: Fri, 14 Aug 2020 19:53:09 -0700	[thread overview]
Message-ID: <CAHk-=wgZ6ZgRWRm0rGgLkYR-_XwKeuWxwbkBWxmCOzt7dGxWpg@mail.gmail.com> (raw)
In-Reply-To: <20200815003102.dzZiwVm-K%akpm@linux-foundation.org>

On Fri, Aug 14, 2020 at 5:31 PM Andrew Morton <akpm@linux-foundation.org> wrote:
>
> From: Minchan Kim <minchan@kernel.org>
> Subject: mm/madvise: check fatal signal pending of target process
>
> Bail out to prevent unnecessary CPU overhead if target process has pending
> fatal signal during (MADV_COLD|MADV_PAGEOUT) operation.

This seems bogus.

Returning -EINTR when *SOMEBODY ELSE* has a signal is crazy talk.

It also seems to be the reason for the previous patches inexplicably
passing in the task pointer.

Finally, it has absolutely no explanations for why this would matter,
and why it's magically and suddenly an issue for process_madvise(),
when in the history of the *real* madvise() this hasn't been an issue
for "current".

I'm dropping the madvise() series.

If the issue is that you can generate a long series or areas with that
iovec, maybe the code should re-consider. Or maybe the signal pending
case should be done there, not passing down an odd task pointer to the
low-level madvise code.

              Linus


  reply	other threads:[~2020-08-15  2:53 UTC|newest]

Thread overview: 49+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-08-15  0:29 incoming Andrew Morton
2020-08-15  0:30 ` [patch 01/39] asm-generic: pgalloc.h: use correct #ifdef to enable pud_alloc_one() Andrew Morton
2020-08-15  0:30 ` [patch 02/39] Revert "mm/vmstat.c: do not show lowmem reserve protection information of empty zone" Andrew Morton
2020-08-15  0:30 ` [patch 03/39] lz4: fix kernel decompression speed Andrew Morton
2020-08-15  0:30 ` [patch 04/39] exec: restore EACCES of S_ISDIR execve() Andrew Morton
2020-08-15  0:30 ` [patch 05/39] selftests/exec: add file type errno tests Andrew Morton
2020-08-15  0:30 ` [patch 06/39] mailmap: add entry for Greg Kurz Andrew Morton
2020-08-15  0:30 ` [patch 07/39] mm: store compound_nr as well as compound_order Andrew Morton
2020-08-15  0:30 ` [patch 08/39] mm: move page-flags include to top of file Andrew Morton
2020-08-15  0:30 ` [patch 09/39] mm: add thp_order Andrew Morton
2020-08-15  0:30 ` [patch 10/39] mm: add thp_size Andrew Morton
2020-08-15  0:30 ` [patch 11/39] mm: replace hpage_nr_pages with thp_nr_pages Andrew Morton
2020-08-15  0:30 ` [patch 12/39] mm: add thp_head Andrew Morton
2020-08-15  0:30 ` [patch 13/39] mm: introduce offset_in_thp Andrew Morton
2020-08-15  0:30 ` [patch 14/39] fs: autofs: delete repeated words in comments Andrew Morton
2020-08-15  0:30 ` [patch 15/39] mm/madvise: pass task and mm to do_madvise Andrew Morton
2020-08-15  0:30 ` [patch 16/39] pid: move pidfd_get_pid() to pid.c Andrew Morton
2020-08-15  0:30 ` [patch 17/39] mm/madvise: introduce process_madvise() syscall: an external memory hinting API Andrew Morton
2020-08-16  8:12   ` Christian Brauner
2020-08-17 15:10     ` Minchan Kim
2020-08-15  0:31 ` [patch 18/39] mm/madvise: check fatal signal pending of target process Andrew Morton
2020-08-15  2:53   ` Linus Torvalds [this message]
2020-08-15  4:59     ` Minchan Kim
2020-08-15 14:57       ` Linus Torvalds
2020-08-15 18:34         ` Minchan Kim
2020-08-16  1:43           ` Linus Torvalds
2020-08-16  5:58             ` Minchan Kim
2020-08-15  0:31 ` [patch 19/39] all arch: remove system call sys_sysctl Andrew Morton
2020-08-15  0:31 ` [patch 20/39] mm/kmemleak: silence KCSAN splats in checksum Andrew Morton
2020-08-15  0:31 ` [patch 21/39] mm/frontswap: mark various intentional data races Andrew Morton
2020-08-15  0:31 ` [patch 22/39] mm/page_io: " Andrew Morton
2020-08-15  0:31 ` [patch 23/39] mm/swap_state: " Andrew Morton
2020-08-15  0:31 ` [patch 24/39] mm/filemap.c: fix a data race in filemap_fault() Andrew Morton
2020-08-15  0:31 ` [patch 25/39] mm/swapfile: fix and annotate various data races Andrew Morton
2020-08-15  0:31 ` [patch 26/39] mm/page_counter: fix various data races at memsw Andrew Morton
2020-08-15  0:31 ` [patch 27/39] mm/memcontrol: fix a data race in scan count Andrew Morton
2020-08-15  0:31 ` [patch 28/39] mm/list_lru: fix a data race in list_lru_count_one Andrew Morton
2020-08-15  0:31 ` [patch 29/39] mm/mempool: fix a data race in mempool_free() Andrew Morton
2020-08-15  0:31 ` [patch 30/39] mm/rmap: annotate a data race at tlb_flush_batched Andrew Morton
2020-08-15  0:31 ` [patch 31/39] mm/swap.c: annotate data races for lru_rotate_pvecs Andrew Morton
2020-08-15  0:31 ` [patch 32/39] mm: annotate a data race in page_zonenum() Andrew Morton
2020-08-15  0:31 ` [patch 33/39] include/asm-generic/vmlinux.lds.h: align ro_after_init Andrew Morton
2020-08-15  0:32 ` [patch 34/39] sh: clkfwk: remove r8/r16/r32 Andrew Morton
2020-08-15  0:32 ` [patch 35/39] sh: use generic strncpy() Andrew Morton
2020-08-15  0:32 ` [patch 36/39] iomap: constify ioreadX() iomem argument (as in generic implementation) Andrew Morton
2020-08-15  0:32 ` [patch 37/39] rtl818x: " Andrew Morton
2020-08-15  0:32 ` [patch 38/39] ntb: intel: " Andrew Morton
2020-08-15  0:32 ` [patch 39/39] virtio: pci: " Andrew Morton
2020-08-19 23:09 ` mmotm 2020-08-19-16-09 uploaded Andrew Morton

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