-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1
On 02/12/2015 02:55 PM, Rik van Riel wrote:
> On 02/12/2015 11:18 AM, Kirill A. Shutemov wrote:
>> @@ -490,6 +493,7 @@ extern int
>> wait_on_page_bit_killable_timeout(struct page *page,
>
>> static inline int wait_on_page_locked_killable(struct page *page)
>> { + page = compound_head(page); if (PageLocked(page)) return
>> wait_on_page_bit_killable(page, PG_locked); return 0; @@ -510,6
>> +514,7 @@ static inline void wake_up_page(struct page *page, int
>> bit) */ static inline void wait_on_page_locked(struct page *page)
>> { + page = compound_head(page); if (PageLocked(page))
>> wait_on_page_bit(page, PG_locked); }
>
> These are all atomic operations.
>
> This may be a stupid question with the answer lurking somewhere in
> the other patches, but how do you ensure you operate on the right
> page lock during a THP collapse or split?
Kirill answered that question on IRC.
The VM takes a refcount on a page before attempting to take a page
lock, which prevents the THP code from doing anything with the
page. In other words, while we have a refcount on the page, we
will dereference the same page lock.
- --
All rights reversed
-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1
iQEcBAEBAgAGBQJU3Qi8AAoJEM553pKExN6D/44H/jUIn9btSRRIje/YBFFib8Dt
Zlvn4bFD6MbFonTQMJA5+vb6s0gxwdkbwLqGKpRo+FHWnKDxCvEpQfxuj708LaCq
1tqjnKIv1xt5bz31pV/UQhdAMcbcyKdEu4udH5mQigh4HIXYhUhe4w9TMUGu/f4U
FTx7dn3FfhQT3qWTVdZubdY/JRIXJcaXYqVIauvXQCRsCHfmx5YHD5YLulXP9OKw
HP0baxtbxP5njNPthbb9T947dcdndbBiwt3+Rnnlw4Ij4fB2kX7kvOC4M8v0eKKA
wKZ7A0sfzp27kJT7N/HlwGOXnX/e28LMbK7zA1avi5JDIIAYQU1Ris67EXTSKlg=
=1q7l
-----END PGP SIGNATURE-----
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@xxxxxxxxx. For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>