path: root/drivers
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authorKOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>2011-05-26 16:25:52 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2011-05-26 17:12:37 -0700
commit30cd8903913dac7b0918807cac46be3ecde5a5a7 (patch)
tree64022195d9a384c11b93a4b1299aa944b8293deb /drivers
parenta4dbf0ec2aa3e8aca6e63f598095750c232d50f1 (diff)
proc: put check_mem_permission after __get_free_page in mem_write
It whould be better if put check_mem_permission after __get_free_page in mem_write, to be same as function mem_read. Hugh Dickins explained the reason. check_mem_permission gets a reference to the mm. If we __get_free_page after check_mem_permission, imagine what happens if the system is out of memory, and the mm we're looking at is selected for killing by the OOM killer: while we wait in __get_free_page for more memory, no memory is freed from the selected mm because it cannot reach exit_mmap while we hold that reference. Reported-by: Jovi Zhang <bookjovi@gmail.com> Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Acked-by: Hugh Dickins <hughd@google.com> Reviewed-by: Stephen Wilson <wilsons@start.ca> Cc: Alexey Dobriyan <adobriyan@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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