+ zram-remove-bd_cap_synchronous_io-with-writeback-feature-v2.patch added to -mm tree

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



The patch titled
     Subject: zram-remove-bd_cap_synchronous_io-with-writeback-feature-v2
has been added to the -mm tree.  Its filename is
     zram-remove-bd_cap_synchronous_io-with-writeback-feature-v2.patch

This patch should soon appear at
    http://ozlabs.org/~akpm/mmots/broken-out/zram-remove-bd_cap_synchronous_io-with-writeback-feature-v2.patch
and later at
    http://ozlabs.org/~akpm/mmotm/broken-out/zram-remove-bd_cap_synchronous_io-with-writeback-feature-v2.patch

Before you just go and hit "reply", please:
   a) Consider who else should be cc'ed
   b) Prefer to cc a suitable mailing list as well
   c) Ideally: find the original patch on the mailing list and do a
      reply-to-all to that, adding suitable additional cc's

*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***

The -mm tree is included into linux-next and is updated
there every 3-4 working days

------------------------------------------------------
From: Minchan Kim <minchan@xxxxxxxxxx>
Subject: zram-remove-bd_cap_synchronous_io-with-writeback-feature-v2

  - description correction - Andrew
  - add comment about removing BDI_CAP_SYNCHRONOUS_IO

Link: https://lore.kernel.org/lkml/0516ae2d-b0fd-92c5-aa92-112ba7bd32fc@xxxxxxxxxx/
Link: http://lkml.kernel.org/r/20180802051112.86174-1-minchan@xxxxxxxxxx
Link: http://lkml.kernel.org/r/20180805233722.217347-1-minchan@xxxxxxxxxx
Signed-off-by: Minchan Kim <minchan@xxxxxxxxxx>
Reported-by: Tino Lehnig <tino.lehnig@xxxxxxxxxx>
Tested-by: Tino Lehnig <tino.lehnig@xxxxxxxxxx>
Cc: Sergey Senozhatsky <sergey.senozhatsky.work@xxxxxxxxx>
Cc: Jens Axboe <axboe@xxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>	[4.15+]
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---


diff -puN drivers/block/zram/zram_drv.c~zram-remove-bd_cap_synchronous_io-with-writeback-feature-v2 drivers/block/zram/zram_drv.c
--- a/drivers/block/zram/zram_drv.c~zram-remove-bd_cap_synchronous_io-with-writeback-feature-v2
+++ a/drivers/block/zram/zram_drv.c
@@ -401,6 +401,16 @@ static ssize_t backing_dev_store(struct
 	zram->backing_dev = backing_dev;
 	zram->bitmap = bitmap;
 	zram->nr_pages = nr_pages;
+	/*
+ 	 * With writeback feature, zram does asynchronous IO so it's no longer
+ 	 * synchronous device so let's remove synchronous io flag. Othewise,
+	 * upper layer(e.g., swap) could wait IO completion rather than
+	 * (submit and return), which will cause system sluggish.
+ 	 * Furthermore, when the IO function returns(e.g., swap_readpage),
+ 	 * upper layer expects IO was done so it could deallocate the page
+ 	 * freely but in fact, IO is going on so finally could cause
+ 	 * use-after-free when the IO is really done.
+ 	 */
 	zram->disk->queue->backing_dev_info->capabilities &=
 			~BDI_CAP_SYNCHRONOUS_IO;
 	up_write(&zram->init_lock);
_

Patches currently in -mm which might be from minchan@xxxxxxxxxx are

zram-remove-bd_cap_synchronous_io-with-writeback-feature.patch
zram-remove-bd_cap_synchronous_io-with-writeback-feature-v2.patch




[Index of Archives]     [Linux Kernel]     [Kernel Development Newbies]     [Linux USB Devel]     [Video for Linux]     [Linux Audio Users]     [Yosemite Hiking]     [Linux Kernel]     [Linux SCSI]

  Powered by Linux