TRY_TO_RELEASE_PAGE(9) Memory Management in Linux TRY_TO_RELEASE_PAGE(9)NAME
try_to_release_page - release old fs-specific metadata on a page
int try_to_release_page(struct page * page, gfp_t gfp_mask);
the page which the kernel is trying to free
memory allocation flags (and I/O mode)
The address_space is to try to release any data against the page (presumably at page->private). If the release was successful, return `1'.
Otherwise return zero.
This may also be called if PG_fscache is set on a page, indicating that the page is known to the local caching routines.
The gfp_mask argument specifies whether I/O may be performed to release this page (__GFP_IO), and whether the call may block (__GFP_WAIT &
COPYRIGHT Kernel Hackers Manual 3.10 June 2014 TRY_TO_RELEASE_PAGE(9)
Check Out this Related Man Page
JOURNAL_TRY_TO_FREE_(9) The Linux Journalling API JOURNAL_TRY_TO_FREE_(9)NAME
journal_try_to_free_buffers - try to free page buffers.
int journal_try_to_free_buffers(journal_t * journal, struct page * page, gfp_t gfp_mask);
journal for operation
to try and free
we use the mask to detect how hard should we try to release buffers. If __GFP_WAIT and __GFP_FS is set, we wait for commit code to
release the buffers.
For all the buffers on this page, if they are fully written out ordered data, move them onto BUF_CLEAN so try_to_free_buffers can reap
This function returns non-zero if we wish try_to_free_buffers to be called. We do this if the page is releasable by try_to_free_buffers. We
also do it if the page has locked or dirty buffers and the caller wants us to perform sync or async writeout.
This complicates JBD locking somewhat. We aren't protected by the BKL here. We wish to remove the buffer from its committing or running
transaction's ->t_datalist via __journal_unfile_buffer.
This may *change* the value of transaction_t->t_datalist, so anyone who looks at t_datalist needs to lock against this function.
Even worse, someone may be doing a journal_dirty_data on this buffer. So we need to lock against that. journal_dirty_data will come out of
the lock with the buffer dirty, which makes it ineligible for release here.
Who else is affected by this? hmm... Really the only contender is do_get_write_access - it could be looking at the buffer while
journal_try_to_free_buffer is changing its state. But that cannot happen because we never reallocate freed data as metadata while the data
is part of a transaction. Yes?
Return 0 on failure, 1 on success
Roger Gammans <firstname.lastname@example.org>
Stephen Tweedie <email@example.com>
COPYRIGHT Kernel Hackers Manual 3.10 June 2014 JOURNAL_TRY_TO_FREE_(9)
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